Avocado oil, butter, or any neutral cooking oil works here. Olive Oil – Used for sauteing the meats and veggies.For measurements, see the recipe card below. This section explains how to choose the best ingredients for a breakfast egg casserole, what each one does in the recipe, and substitution options. From busy weekdays to holiday morning brunch, breakfast casserole recipes are a staple in my house. You can even prepare it the night before and bake it the next day, making your mornings smoother than ever. Plus, this breakfast egg casserole is incredibly easy to whip up. You can use any protein, veggies (or potatoes), and cheese you like or have on hand - I’ll show you my foolproof formula below. Tired of rushing through your mornings without a healthy breakfast, or not sure what to make for brunch for a special occasion? This totally customizable, easy breakfast casserole recipe is here to save the day! It’s based on my keto breakfast casserole, but even more custom for any lifestyle. What To Serve With Breakfast Casserole Recipes.Formula For An Easy Breakfast Casserole.Why You’ll Love This Easy Breakfast Casserole Recipe.