6 Tips for Better Breakfast Casseroles, Straight from Our Test Kitchen
1. Don't toast the nuts
Although we usually recommend toasting nuts before you cook with them, you can skip this step when making a casserole. Untoasted nuts will brown nicely as the casserole bakes, and won't burn.
2. Rest the streusel
Yes, I know that sounds weird. If your casserole has a streusel topping, mix the ingredients with melted butter until it is combined, then set the bowl aside for 20 minutes or so. You can also pop it in the fridge for 10 minutes. This gives the dry ingredients more time to absorb the wet ingredients so you can break the mixture up into small and large chunks for the topping.
3. Chill it thoroughly
If you're making a casserole with bread, make sure that it spends enough time in the refrigerator so it can fully absorb the dairy-egg mixture. Don't rush this step, or you'll prevent it from baking evenly and might make the texture dry in spots. At the same time, don't let it sit too long before baking it—you don't want it to be soggy either.
4. Thaw the hash browns
Frozen hash browns make a great addition to a breakfast casserole. Be sure to thaw the potatoes before you use them. Once defrosted, they will be easier to stir together and will take less time to bake. Frozen potatoes might release too much liquid, which could water down the casserole.
5. Cover the top
Covering the dish with aluminum foil for the first part of the bake time helps the casserole heat through to the center without drying out on top. Remove the foil for the last half of the bake time so that the top can crisp up.
6. Use full-fat dairy
Breakfast casseroles should be indulgent. This is not the time to use low-fat milk instead of cream (the custard will be watery), or cut back on the cheese. If you want to make a casserole healthier, look for recipes that are loaded with vegetables, or make it meatless.