Quite honestly, the first thing that came to mind was maque choux. It's fantastic, and really easy to make. I make a variation of a recipe from Emeril that I think works well.
1/2 stick of unsalted butter
8 cups of corn (frozen kernels are fine)
1 medium yellow onion, diced
1 red bell pepper, diced
2 cloves garlic, minced
1/4 cup minced jalepenos (serranos or other peppers will also work fine)
1/2 cup heavy cream
juice of 1/2 small lemon
cayenne pepper (optional)
fresh herbs (chives, oregano, or thyme work best)
Melt the butter. Cook onions and bell peppers until almost tender. Add garlic, corn, jalepenos, salt, pepper, and cayenne pepper (if you wish to add more heat). Cook until everything is cooked through, about 10 minutes. Add heavy cream and adjust seasoning. Garnish with fresh herbs.
There are literally hundreds of variations of this classic dish. It also works well if you pour the mixture into a casserole dish, cover with cheese and broil. You can also add seafood if you like.
Heat a big skillet way hot, and have the oven on -- temp doesn't really matter, but not 500 or something. When the skillet is blazing, add a little oil and pour in a whole bunch of frozen corn kernels. Toss, add salt, and toss. Keep tossing until there is quite a bit of definite browning going on, some of the kernels are popping, and so on. Takes 5-6 minutes, give or take. Meanwhile, nuke a smaller amount of frozen baby peas with a little water and a lid on top, just to make them hot, not to really boil them. When the corn is done, drain the peas and pour them in. (Peas and carrots mix is dandy too, but be sure the peas are sweet baby peas so it doesn't get all starchy.) Toss a few times, shut off the heat, and pour the mixture into a heatproof serving dish. Put a fair pat of butter on top and shove it in the oven. If it needs to sit more than 10 minutes, put foil on top. When you're ready, stir and serve immediately.
My kids, who admittedly eat a good range of things considering they're 3 and 5, need to be restrained from eating this. Literally: we give them heaping serving spoonfuls at a time, and wait. Otherwise they'll eat it so fast they choke. Not exaggerating. Adults usually notice that the corn has a lot of the good flavors of buttered popcorn but hasn't lost its juicy flavor, and the peas (and carrots) make it even better. You can add shucked soybeans (edamame) if you like, or replace the peas, but my kids would rather you didn't.
I'm going to make either a maque choux or the recipe that ChrisL described. I have to choose the one that can be best served at room temp since i'm not serving it at my house. Which one do you think would sit better? They both sound delicious as do all the recipes shared. You cannot go wrong when corn is involved.
Maque choux can be eaten cold, but I would definitely recommend reheating. If you wanted to make it into a gratin, make the maque choux, pour it into your casserole dish, and put the cheese in a separate container. When you get to your hosts' house, you can bake the casserole for a few minutes to reheat, then top with the cheese and broil. If you want to stay the more classic route, just bake in the casserole for a few minutes and serve. Hope everything works out well for you!