Make a super easy and delicious breakfast casserole that everyone will love. Change it up a bit if you like and add bacon or ham, bell pepper, or substitute other favorite ingredients.
2 T. olive oil, plus more if needed
1 T. unsalted butter
1 medium yellow onion, finely chopped
4 c. assorted sliced mushrooms
salt, to taste
1 c. fresh spinach, chopped
several basil leaves
2 medium tomatoes, thinly sliced
3/4 c. shredded mozzarella cheese
6 large eggs (or whatever you need)
freshly ground black pepper, to taste
In a large skillet over medium heat, heat olive oil and butter; cook onion, stirring frequently, until translucent, about 5 minutes.
Add mushrooms; season with salt; cook, stirring frequently, until mushrooms have released their juices and browned, about 10 minutes. If needed, add a splash of olive oil; stir in spinach and basil; cook until wilted, about 2 minutes. Remove from heat; spoon into a casserole dish; cool for 10 minutes or overnight.
When ready to bake, preheat oven to 350 degrees.
If the mushroom mixture was chilled overnight, warm it in the oven for 15 minutes before proceeding. Then arrange the tomatoes over the mushroom mixture; sprinkle cheese over the vegetables. Carefully crack the eggs on top of the mixture, keeping the yolks intact; season with salt and pepper, to taste.
Bake until egg whites are set and yolks are still a bit runny, about 15-20 minutes. The eggs will continue cooking a bit more once removed from the oven. Make sure you watch the eggs in the oven carefully. There’s a sweet spot when the whites are set but the yolks remain runny. If you cook just a minute too long the yolks will harden.