Potatoes Au Gratin - Par boil or no?

6
0
Joined Dec 27, 2021
I'm the pastry chef at a cafe and bakery in Lexington KY. We've been working through recipes that have just been a pain in the ass, and the one we can't seem to find a diffinative answer on is how to do potatoes au gratin. I would say ours are more in the Dauphinoise category from what I've read, but they still aren't as good as they could be. We always have too much liquid afterward (Obviously we need to reduce this), they take FOREVER to bake, they boil over in the oven, the potatoes on the bottom burn by the time it's all cooked. It's just a mess. SO, in brainstorming, should we be par boiling/baking the potatoes whole, cooling, then slicing and baking in the pans? Are we just doing it all wrong from the get go? They're sliced pretty thin on a mandolin, we heat the cream/milk base before adding to the potatoes. We use a half sheet pan. Should we be starting with cold liquid? Less cream more milk? Start in a cold oven?

Like I said, I am a pastry chef, not a chef. While I know some things about the savory world, I am by no means all knowing. Any input would be greatly appreciated!
 
2,280
738
Joined Oct 31, 2012
If you are making them directly on a half sheet pan, then that's a big reason for the spillage, etc.
For commercial purposes I'd use a hotel pan.
Here's a recipe I just did for Christmas dinner.
Start with mise en place, making sure all things are ready.
Then slice raw peeled potatoes on mandolin. Do not rinse potatoes.
Drizzle some heavy cream, kosher salt and white pepper in bottom of pan.
(At home I used a large oval porcelain cast iron casserole dish but a hotel pan should be fine.)
Lay down the fIrst shingled layer of potatoes. Do this neatly, try to use similar size slices, save the smaller pieces for filling if need be or another use. Don't just toss the potatoes in randomly.
A bit more heavy cream, dust some flour over. I use a fine strainer and by dusting I mean very little flour.
Sprinkle some sliced shallots on the potatoes. Then Grate Gruyere cheese over the layer. Or use whatever cheese you like but gruyere goes well with potatoes.
A light sprinkle of kosher salt and white pepper.
Second layer of potatoes, shingled. You can shingle perpendicular to first layer. I think it helps with stability when cutting and serving.
again with heavy cream, flour, cheese, salt and white pepper, etc. .
Keep repeating until pan is full. top with grated cheese.
Place hotel pan on sheet pan to control overspill if any.
Bake 275-300 uncovered until top is browned and bubbly.

Cook it slow so the heavy cream, flour and potato starch all have a chance to blend and thicken.
A bechamel or cheese sauce would probably work too but it was Christmas dinner so I went with heavy cream.
Scalloped potatoes are the same with no cheese, just heavy cream and onions.
 
Last edited:
3,330
753
Joined May 5, 2010
Nice recipe chefwriter.
Using raw uncooked potatoes causes the extra liquid.
I cook my potato slices in heavy cream. Halfway done, I spoon the potato slices into a buttered au gratin dish, season, then pour a little of the cream mixture on top and sprinkle shredded Gruyere on top. Then it goes in a hot oven to brown and finish.
 
2,280
738
Joined Oct 31, 2012
Thank you.
I find the sprinkle of flour helps absorb the moisture from the potatoes while cooking and if done lightly isn't noticeable and prevents overspill.
 
183
45
Joined Jan 17, 2015
Chefross method is the one I have been using for years and it works for me. I add finely chopped garlic and thyme to the potato & cream mix . Seasoning the gratin correctly is critical.
 
6
0
Joined Dec 27, 2021
If you are making them directly on a half sheet pan, then that's a big reason for the spillage, etc.
For commercial purposes I'd use a hotel pan.
Here's a recipe I just did for Christmas dinner.
Start with mise en place, making sure all things are ready.
Then slice raw peeled potatoes on mandolin. Do not rinse potatoes.
Drizzle some heavy cream, kosher salt and white pepper in bottom of pan.
(At home I used a large oval porcelain cast iron casserole dish but a hotel pan should be fine.)
Lay down the fIrst shingled layer of potatoes. Do this neatly, try to use similar size slices, save the smaller pieces for filling if need be or another use. Don't just toss the potatoes in randomly.
A bit more heavy cream, dust some flour over. I use a fine strainer and by dusting I mean very little flour.
Sprinkle some sliced shallots on the potatoes. Then Grate Gruyere cheese over the layer. Or use whatever cheese you like but gruyere goes well with potatoes.
A light sprinkle of kosher salt and white pepper.
Second layer of potatoes, shingled. You can shingle perpendicular to first layer. I think it helps with stability when cutting and serving.
again with heavy cream, flour, cheese, salt and white pepper, etc. .
Keep repeating until pan is full. top with grated cheese.
Place hotel pan on sheet pan to control overspill if any.
Bake 275-300 uncovered until top is browned and bubbly.

Cook it slow so the heavy cream, flour and potato starch all have a chance to blend and thicken.
A bechamel or cheese sauce would probably work too but it was Christmas dinner so I went with heavy cream.
Scalloped potatoes are the same with no cheese, just heavy cream and onions.
Should have clarified, not a standard half sheet. It's 2" tall, so very similar to a hotel pan.

Every recipe I see does not use flour at all, and there is also a need to keep it a gluten free option unfortunately.
 
6
0
Joined Dec 27, 2021
Nice recipe chefwriter.
Using raw uncooked potatoes causes the extra liquid.
I cook my potato slices in heavy cream. Halfway done, I spoon the potato slices into a buttered au gratin dish, season, then pour a little of the cream mixture on top and sprinkle shredded Gruyere on top. Then it goes in a hot oven to brown and finish.
Nice recipe chefwriter.
Using raw uncooked potatoes causes the extra liquid.
I cook my potato slices in heavy cream. Halfway done, I spoon the potato slices into a buttered au gratin dish, season, then pour a little of the cream mixture on top and sprinkle shredded Gruyere on top. Then it goes in a hot oven to brown and finish.
Great tip on the uncooked potatoes causing excess liquid. I was wondering if this was the case.
 

kuan

Moderator
Staff member
7,151
562
Joined Jun 11, 2001
When I make it I hardly use garlic. In fact I just crush one clove of garlic and rub it on the inside of the terrine. I always make sure the cream is hot and I cook it covered. Halfway through I remove and crush the potatoes down, then cover and bake until it's done. When it's fully done I crush it down again and make the top nice and flat, add cheese, bake until brown.
 
2,280
738
Joined Oct 31, 2012
If gluten isn't acceptable you could substitute potato starch, used in the same manner. It's simply a starch addition to help absorb the moisture.
Or use Chef Ross's method.
I mentioned cooking at 275-300 because that's what I do but also because you posted that they boil over and the bottom is burnt. That tells me your heat is too high.
The whole mixture needs even, gentle heat to cook evenly all throughout and allow time for the potato starch and fat from heavy cream to blend and to absorb the water the comes out of the potato. Too high heat makes it boil and splatter. The dish should also be cooked when room temperature to help insure even heating so just after assembling is good. At too high a heat, the bottom of the pan will be too hot before the center has a chance to warm up. So you end up with cooked potatoes around the outside that have already released their water while the center is still releasing water.
In any case, they should be done in 45 minutes to an hour, especially in a convection oven.
A two inch deep pan should be fine but can't be overloaded. Potato layers should be even across the pan and should be slightly less than the top of the pan. As they cook they shrink but not that much and the extra potato means releasing extra liquid, another reason for the overflow.
 
11
5
Joined Jun 16, 2021
I'm the pastry chef at a cafe and bakery in Lexington KY. We've been working through recipes that have just been a pain in the ass, and the one we can't seem to find a diffinative answer on is how to do potatoes au gratin. I would say ours are more in the Dauphinoise category from what I've read, but they still aren't as good as they could be. We always have too much liquid afterward (Obviously we need to reduce this), they take FOREVER to bake, they boil over in the oven, the potatoes on the bottom burn by the time it's all cooked. It's just a mess. SO, in brainstorming, should we be par boiling/baking the potatoes whole, cooling, then slicing and baking in the pans? Are we just doing it all wrong from the get go? They're sliced pretty thin on a mandolin, we heat the cream/milk base before adding to the potatoes. We use a half sheet pan. Should we be starting with cold liquid? Less cream more milk? Start in a cold oven?

Like I said, I am a pastry chef, not a chef. While I know some things about the savory world, I am by no means all knowing. Any input would be greatly appreciated!
Cooking duration is purely a function of the type of potato used. Waxy ones will take longer but hold their shape better. A gratin shouldn't be cooked too hot: 150C/300F. The way to control moisture is to only add the cream/milk mix as needed: you moisten everything nicely before going to teh oven and then you check every 10-15 minutes and top up as needed. You cook covered in foil until done, then you give it another 10 minutes without foil to colour. This can be made in advance and reheated to order.
 

Latest posts

Top Bottom