This easy Brunch Egg Bake is a make-ahead breakfast casserole packed with eggs, spinach, mushrooms, potatoes, and cheddar cheese. Perfect for holidays, meal prep, or weekend brunch!
Arrange a rack in the middle of the oven and heat to 375°F. Coat a 9x13-inch baking dish with olive oil and set aside.
Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add mushrooms, green onions, and red bell pepper. Cook for about 5 minutes until tender. Add spinach and cook until wilted and most liquid has evaporated (about 5 minutes). Remove from heat and stir in frozen diced potatoes.
Transfer the vegetable mixture into the prepared baking dish and spread evenly. Sprinkle cheddar cheese evenly over the top.
In a large bowl, whisk together the eggs, half and half, salt, and black pepper. Pour evenly over the vegetables and cheese.