Saute the onion in oil.
Stir in the spices and salt. Cook for a minute.
Add the beans, rice, cheese, milk and then eggs. Mix to combine.
Bake at 350 degrees for about 25 minutes or until the center is set.
I used an iron skillet to bake mine. If you don’t have an oven proof skillet, you can transfer the casserole to a baking dish.
Serve with salsa.