Slow and low is the best way to bake an egg casserole to make sure it doesn’t fall in on itself. The bake time for an egg casserole is 55 to 65 minutes with an oven set to 350 degrees. You can be sure your egg casserole is fully baked through when you take it out of the oven and stick a knife into the center of it. If it comes out clean, then your baked egg casserole is ready to eat. The casserole should also be firm, not wet. A delicious egg casserole recipe can be a simple addition to your morning meal.