Healthy Breakfast Casserole

0 Preheat the oven to 350 degrees Fahrenheit. Heat the oil in a skillet over medium heat, then add the diced onion. Cook for two to three minutes or until translucent. Be careful not to burn the onion!
1 Add the crushed garlic, bell peppers, and sliced mushrooms. Cook until all the vegetables are soft and remove them from the heat. 
2 In a bowl, whisk together the eggs, cream, salt, and pepper. Mix until everything is fully combined. 
3 Grease a 7x11-inch casserole dish with nonstick spray so the eggs do not stick to the sides. Drain the excess liquids from the cooked vegetables and spread an even layer into the bottom of the dish. 
4 Next, layer the frozen, thawed spinach on top of the vegetables and pour the egg mixture over them. Top the eggs with feta and cheddar cheese. 
5 Bake the casserole in the preheated oven for 30-45 minutes until cooked through completely. The center should not be able to wiggle when shaken and the color of the casserole should be lightly golden brown.
6 Remove the casserole from the oven and allow it to cool for ten minutes before serving. Cut the casserole into 12 individual pieces and enjoy!