Step 1: Sauté the Aromatics and Veggies: Heat a tablespoon of olive oil or butter in a large skillet over medium heat. Add the diced onion and bell pepper. Sauté for about 5-7 minutes, or until softened and fragrant. If you’re adding other vegetables like mushrooms or spinach, add them now and cook until any excess moisture has evaporated. Season with a pinch of salt and black pepper.
Step 2: Prepare Your Baking Dish: Preheat your oven to 375°F (190°C). Lightly grease a 9×13 inch baking dish with butter or cooking spray. This prevents sticking and ensures your egg casserole recipe comes out cleanly. For easy meal prep and storage, consider using high-quality Basics Glass Food Storage containers, perfect for keeping leftovers fresh.
Step 3: Whisk the Egg Mixture: In a large bowl, whisk together the eggs, milk (or cream), Dijon mustard, salt, black pepper, garlic powder, and onion powder until well combined and slightly frothy. Ensure the mixture is homogenous for an even consistency throughout the casserole.
Step 4: Layer the Casserole: Spread the sautéed vegetables evenly across the bottom of the prepared baking dish. Sprinkle about half of the shredded cheese over the vegetables. If you’re adding cooked meat, layer it over the cheese.
Step 5: Pour and Top: Carefully pour the whisked egg mixture over the vegetables and cheese in the baking dish. Gently shake the dish to ensure the egg mixture settles evenly. Sprinkle the remaining shredded cheese over the top.
Step 6: Bake to Golden Perfection: Bake the casserole in the preheated oven for 35-45 minutes, or until the center is set, the edges are golden brown, and a knife inserted into the center comes out clean. If the top starts to brown too quickly, loosely cover it with foil.
Step 7: Rest and Serve: Once baked, remove the egg casserole recipe from the oven and let it rest for 5-10 minutes before slicing and serving. Garnish with fresh chopped chives or parsley if desired.