My first thought is to use a larger casserole dish. Also might have something to do with the amount of sauce you have on your scalloped potatoes.

I always cook my sliced potatoes in cream before adding them to the casserole. This brings out the starch from the potatoes and thickens the sauce without having to add flour.

~Ann

I took Ann T.'s suggestion several years ago and started boiling the potatoes in the cream before baking. It works great. Bakes faster and it's easy to gauge the size dish required because it will have already thickened.

/tricia

This post was edited by triciae on Mon, Jul 22, 13 at 18:29

Thank you will try cooking potatoes in cream...

Clair, Once the potatoes have cooked in the cream and started to thickened, they get poured into a butter casserole and are finished in the oven.

Potato Gratin

I don't usually follow a recipe when making a Potato Gratin. Use the following as a guideline and adjust everything to your own taste.

For a rich dish, use butter and whipping cream.

3 to 5 Russet Potatoes (or more depending on number of servings required)
1 garlic clove
1 teaspoon fresh thyme (optional)
Butter
Heavy Cream (or milk if you want a less rich version)
Parmesan cheese
Gruyere cheese as well as cheddar and blue cheeses can be added for a different taste all together.
Salt and pepper

Rub cut garlic clove over the surface of a gratin or casserole dish. Butter.

Slice potatoes and place in pot and add enough cream/milk to almost cover. Add the garlic clove, thyme, salt and pepper. Bring to a boil and simmer for a few minutes, stirring often so the potatoes do not stick. When the potatoes have released some of their starch and thickend the liquid, remove the garlic clove, add 1 to 2 tablespoons butter and some grated Parmesan cheese. Pour into prepared casserole dish, dot with butter and sprinkle with some more Parmesan cheese. TIP: If you like a more garlicky flavour, just grated a garlic clove on a microplane and add to the cream mixture.

Bake in a 375ðF oven for 45 to 55 minutes or until potatoes are tender. Remove from oven and let sit for 10 minutes before serving.
Another way to make a potato Gratin is to saute some thinly sliced onions in olive oil or butter until golden, add some thyme, and some chicken broth. Add the potatoes, salt and pepper and bring to a boil. Pour into a buttered casserole dish sprinkle with some Parmesan cheese and bake until cooked.

Pre-cooking is a good idea. Never tried that. I usually layer slices with thinly sliced onion, garlic, a bit of cheese, fresh rosemary, repeat layers, top with parmesan, add a 1/2 cup yogurt milk, (non-fat yogurt thinned with water). Cover with foil and bake at 400 for 15 min, then turn down to 325 for the final half hour-45 min uncovered. Dropping the temp down prevents a boil over. (I probably do not use enough liquid for a spillover.)
I often use a sliced sweet potato as the bottom layer. Cooks faster and adds a nice creamy texture since i have been cutting out the extra calories.

I, too, use Ann's method. It makes a world of difference in the finished product. No boil overs and no emergency additions of liquid because the potatoes aren't cooked enough. Plus you get all the hard work done on top of the stove. Oven time is cut quite a bit, which is really good news in the summer months.

I've successfully used Ann's second method too -- using chicken broth instead of cream/milk. And I've made a combo of both methods to cut the richness somewhat. Initial cooking with broth with a bit of heavy cream added to the mix just before pouring into a casserole. I've even cooked the whole thing on top of the stove on those days when I'm craving scalloped potatoes but don't want to turn the oven on at all.

I too use Ann's method but make sure you only cook until slightly tender. You do not want to cook the potatoes too much in the cream or broth......just until they release some strarch but are still very firm.

Since I read about it, I have used the Ann method of pre-cooking too but I use canned evaporated milk instead of the cream.