Overnight Egg Casserole

I am a big fan of egg and sausage casseroles, but I haven't attempted one since going paleo since a large component of many recipes is cheese or bread. I put this one together with some of my favorites, sausage, mushrooms, and onions. In this version I used chorizo, but any Italian sausage would be great here, too. Anything with clean ingredients. I kept this milder that I normall would since some of our guests don't like spicy foods (and I was already pushing the envelope with the chorizo). If you like spice, you could throw in a little cayenne, too. Enjoy!

Ingredients
1 pound bulk sausage (I used chorizo)
1 medium red onion, chopped
2 large cloves garlic, minced
16 ounces fresh mushrooms, chopped
18 large pastured eggs
1 small package fresh basil leaves cut chiffonade (in thin ribbons)
1/2 tsp sea salt
1/4 tsp freshly ground black pepper
1/2 tsp paprika
1/2 tsp chili powder

Preparation

1. Brown chorizo in a large skillet over medium heat until cooked through, about 5 minutes.
2. Remove sausage with a slotted spoon into a 9x13 casserole dish, letting the fat drain back into the skillet. 
3. Remove all but about 1 Tbsp fat from the skillet and add onion, garlic, and mushrooms. Saute over medium heat for 5 minutes. Spoon mixture over chorizo.
4. Break eggs into a large bowl. Add seasonings. Blend with an electric hand mixer until frothy on top, about 4 minutes.
5. Pour into casserole dish. Cover dish and refrigerate overnight.
6. In the morning, preheat oven to 350 degrees F.
7. Bake casserole for 40 minutes or until browned on top and firm in the middle.
8. Sprinkle basil over the top and season with additional salt and pepper, if desired.