# How can potatoes sliced so thinly take so long to cook!?



## kimmit (Feb 28, 2013)

This is one reason I do not make this often. I have had a potato bake (sliced potatoes, cream, milk, garlic and nutmeg) cooking in oven at 180 degrees C, for well over an hour....nowhere near cooked. 
What am I doing wrong? This is how it goes every time!


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## kuan (Jun 11, 2001)

You have a few options.

1)  Start with hot cream and milk

2)  Cook them on the stovetop partially before transferring them to a baking dish and putting it in the oven.


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## grande (May 14, 2014)

How deep do you them layered? I usually plan on an hour and a half, i do them about an.inch and a half...BUT I do slightly thickker slices so there is more space for the milk toheat up. For very thin slices i like to do just butter, start on the stove top in a nonstick on low heat and finish in yhe oven. Flip it when I take it out for a kind of pommes anna.


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## chefedb (Apr 3, 2010)

180 not hot enough 325  to 375 F   better.  pan can be covered then cover off last 10 minutes or so


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## mtullius (Feb 20, 2014)

chefedb said:


> 180 not hot enough 325 to 375 F better. pan can be covered then cover off last 10 minutes or so


She said 180 C. That is 356 F


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## chrisbelgium (Oct 2, 2010)

I'm behind both Kuan's options for this "gratin dauphinois" as it's called.

Since I saw the famous Ann Sophie Pic demonstrate how she makes them, I always use her method;

Use waxy potatoes. I prefer type "Charlotte". Boil the slices in the milk/cream/garlic/bay leaf/s&p mixture for 3 minutes. Transfer the potato slices with a slotted spoon to your ovendish, then cover with the liquid. Bake at 180°C. This method takes about 40-45 minutes.

Adding cheese (a bit of Gruyère or Emmenthal or a mix of both) is optional and delicious but does not really belong there according to the purists; you don't hear me condemning cheese at all.


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## chefross (May 5, 2010)

Chris....your method is same as mine.

I use Russets with no problems.

When I add Gruyere to it I call it Pomme Gratin.


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## chrisbelgium (Oct 2, 2010)

No dought, there must be a range of type of potatoes that are fit for this use, Ross. I mentioned Charlotte because I thought I remembered that @kimmit lives in France where that variety is widely available. Good of you to add a suggestion that will be more suitable for readers on the other side of the Pond.


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## thatchairlady (Feb 15, 2012)

Seem to remember seeing thin sliced potatoes (for scalloped or gratin-ed) getting a 2-3 minute boil/blanch first... Maybe on Cooks Country or ATK??  Something to do with preventing that watery thing that sometimes happens?  You would THINK, if you can bake a big one in maybe an hour, thin sliced should cook faster??


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## kimmit (Feb 28, 2013)

Thank you so much for all your replies. - all very helpful.  I don't know why I didn't think of boiling the potatoes a bit first off.  That makes so much sense.  I will have to try another potato bake soon!  Thanks again.


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## someday (Aug 15, 2003)

Do you have enough liquid in the dish with the potatoes? If you lack liquid, it might take longer. Also, are your potatoes cut thinly and evenly? If your potatoes are inconsistent this might lead to problems too.


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## kimmit (Feb 28, 2013)

Thanks Line Cook. Yup, potatoes were cut paper thin using a kenwood magimix thingy with the blades, and it was swimming in liquid - mixture of cream and milk.  I will try it again this week, and par boil the potatoes before layering them.


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## someday (Aug 15, 2003)

I wouldn't par boil them...the point of cooking them in the dish is that the starch from the potatoes holds the dish together. If you par boil you will lose most of the starch. Unless you par boil them in the milk/cream mixture to keep the starch in the cooking liquid. But what is the point of that, since it just mean more work.


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## kimmit (Feb 28, 2013)

oh dear, ok.  So back to the drawing board I guess.  I will just have to give myself a lot more time I suppose.   Thanks for all the replies and comments, it really interesting to hear everyone's ideas on this.  I did have the sliced potatoes in water overnight (just no time to do everything!) so I suppose that got rid of some of the starch as well?


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## phatch (Mar 29, 2002)

My experience with Gratin Dauphinois is that elevation factors into it. All the classic recipes I've tried for it curdle the dairy at my elevation. I think it's because of my lower boiling point so I lose more liquid to evaporation and the potatoes need a bit more time to cook as well with the lower heat of boiling at my altitude. 

Pre boil helps, but it still curdles. So I've taken to using a bechamel to strengthen the sauce. Cook the potatoes in the milk. Pour off the milk into your roux and make the bechamel. Layer the potatoes and bechamel and bake. This works for me. But it will likely horrify the purists.


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## kimmit (Feb 28, 2013)

Thanks phatch, that is an interesting take on it.  I am not that concerned about doing it the "right" way, so your idea may well be a good alternative - just after a tasty potato dish! 

Thanks!


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## ordo (Mar 19, 2009)

There're some nice variations using baked potatoes. This one looks ok to me:


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## mike9 (Jul 13, 2012)

I need to make that - thank you Ordo /img/vbsmilies/smilies/chef.gif


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## kimmit (Feb 28, 2013)

Thanks Ordo, will definitely try.


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## chrisbelgium (Oct 2, 2010)

Someday said:


> I wouldn't par boil them...the point of cooking them in the dish is that the starch from the potatoes holds the dish together. If you par boil you will lose most of the starch. *Unless you par boil them in the milk/cream mixture to keep the starch in the cooking liquid.* *But what is the point of that, since it just mean more work.*


Indeed, they need to be pre-boiled in the cream/milk mixture and certainly not in water! That particular cream/milk mixture has to used in the oven dish too. And, the potato slices cannot be rinsed at all, you need the starch that covers the slices. The real point of precooking is that all your potatoes will be cooked evenly. When you start with a cold preparation there will always be a range of unevenly cooked potatoes. I cut my slices at approx. 3-4 mm. If you pre-boil you cannot cut too thin slices or you will break them when filling the oven dish.

Another suggestion that kuan already mentioned in one of the first posts, is "to start with hot cream and milk" as he mentioned. When you really do not want to pre-boil the slices, make them quite thin and don't rinse, grease the oven dish with butter first, put the potato slices in and then heat the seasoned cream/milk mixture first on the stovetop before pouring it over the slices. If the gratin colors too fast in the oven, put a sheet of alu foil on top but remove it the last 15 minutes of the baking.

@phatch Which ratio milk/cream do you use? It is true that many times it curdles, I had that experience a lot of times. I heared it has to do with too high evaporation in which the fat content becomes too high. That's why you use a combination of cream with milk to keep the fat content right so it doesn't curdle. Also, the starch of the potatoes should do its work and give a little binding. But, it's always looking out for a perfect gratin coming out of the oven. Theory and practice are often very different!


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## kuan (Jun 11, 2001)

Also at some point too, like three quarters of the way cooked you get the spatula and press the potatoes down into the dish so you pack them nice and tight.


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## grande (May 14, 2014)

If you backed it in say, a nice saute pan with a metal handle, you could arrange them in the dish, poor over your milk and cream, heat on the stove, transfer to oven and finish. Easy money!


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## foodpump (Oct 10, 2005)

Someday said:


> I wouldn't par boil them...the point of cooking them in the dish is that the starch from the potatoes holds the dish together. If you par boil you will lose most of the starch. Unless you par boil them in the milk/cream mixture to keep the starch in the cooking liquid. But what is the point of that, since it just mean more work.


Huh? Why more work? I've been doing it that way for about 30 years now. Slice the spuds, throw them in just enough milk or milk/ cream to cover, blanch, when just tender scoop out and lay in a buttered gratin dish. Reduce the milk mixture a bit, season, pour over the spuds, sprinkle cheese, or bread crumbs or what ever if desired, and bake.


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## cheflayne (Aug 21, 2004)

ChrisBelgium said:


> @phatch Which ratio milk/cream do you use? It is true that many times it curdles, I had that experience a lot of times. I heared it has to do with too high evaporation in which the fat content becomes too high. That's why you use a combination of cream with milk to keep the fat content right so it doesn't curdle.


Contrary to what most people might think, higher fat dairy (such as manufacturing cream) is less likely to curdle than less fat dairy (such as 1/2&1/2 or milk) when reducing. Manufacturing cream, and the like, are also not affected as much by elevation. I lived at 8,000 ft for 10 years and was amazed by how much elevation affects cooking and not just baking. Try making hollandaise at high elevation!!!


phatch said:


> My experience with Gratin Dauphinois is that elevation factors into it. All the classic recipes I've tried for it curdle the dairy at my elevation.


Patch, have you tried it using straight manufacturing cream for your liquid? In my experience, at elevation, it should work without curdling.


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## phatch (Mar 29, 2002)

I've never had that grade of cream to work with.


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## cheflayne (Aug 21, 2004)

Heavy whipping cream that you can get at most grocery stores is close to the same thing, just slightly lower fat, but close enough.


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## steve tphc (Sep 18, 2012)

chefedb said:


> 180 not hot enough 325 to 375 F better. pan can be covered then cover off last 10 minutes or so


Obviously you don't use metric


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## kimmit (Feb 28, 2013)

ChrisBelgium said:


> Indeed, they need to be pre-boiled in the cream/milk mixture and certainly not in water! That particular cream/milk mixture has to used in the oven dish too. And, the potato slices cannot be rinsed at all, you need the starch that covers the slices. The real point of precooking is that all your potatoes will be cooked evenly. When you start with a cold preparation there will always be a range of unevenly cooked potatoes. I cut my slices at approx. 3-4 mm. If you pre-boil you cannot cut too thin slices or you will break them when filling the oven dish.
> 
> Another suggestion that kuan already mentioned in one of the first posts, is "to start with hot cream and milk" as he mentioned. When you really do not want to pre-boil the slices, make them quite thin and don't rinse, grease the oven dish with butter first, put the potato slices in and then heat the seasoned cream/milk mixture first on the stovetop before pouring it over the slices. If the gratin colors too fast in the oven, put a sheet of alu foil on top but remove it the last 15 minutes of the baking.
> 
> @phatch Which ratio milk/cream do you use? It is true that many times it curdles, I had that experience a lot of times. I heared it has to do with too high evaporation in which the fat content becomes too high. That's why you use a combination of cream with milk to keep the fat content right so it doesn't curdle. Also, the starch of the potatoes should do its work and give a little binding. But, it's always looking out for a perfect gratin coming out of the oven. Theory and practice are often very different!


Thanks Chris - Interesting. I am learning about the starch and how it affects different dishes.


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