If desired line a 6.5 quart slow cooker with a Crock-Pot Liner and then spray the liner with non-stick cooking spray to help make removal of the casserole and clean up easier.
In a medium mixing bowl mix together the eggs, evaporated milk, red pepper flakes, salt, pepper and one cup of the cheddar cheese and one cup of the mozzarella cheese. Set aside the remaining cheese for later.
Wash and slice your potatoes fairy thin. I kept the peels on mine but you can remove the peels first if you choose. Take half of the sliced potatoes and lay them at the bottom of the crock.
Spread half of the browned ground sausage on top of the potatoes.
Sprinkle half of the yellow onion and then 1/2 of the remaining cheddar and Mozzarella Cheese. We will then repeat the layers.
Layer the rest of the potatoes.
Layer the rest of the browned sausage.
Next layer the remaining chopped yellow onion.
Next layer the remaining cheddar and mozzarella Cheese.
Carefully pour the egg mixture over your entire potato and sausage mixture. You’ll want to get all of it covered.
Sprinkle the green onions on top.
Cook on LOW for 5 to 6 hours or on HIGH for 3 hours or until the eggs are set. A meat thermometer registering at 160° F means it’s done.
Sprinkle the top of the cooked casserole with freshly grated Parmesan cheese and paprika before serving if desired and enjoy!