Sweet potatoes are the star in this breakfast casserole recipe. We start the recipe with a quick and easy hack for tenderizing the potatoes—pop them in the microwave! Put the spuds in a microwave-safe bowl with water, cover with plastic wrap, and cook on HIGH until they're tender, probably around 4 minutes. Next, brown the sausage in a skillet. A mixture of eggs, half-and-half, and Italian seasoning will serve as the base of your frittata. You’ll stir together all of your ingredients and 1 cup of mozzarella cheese before adding it all to your lightly greased 5-quart slow cooker. Sprinkle the top with the remaining cup of mozzarella cheese before setting your slow cooker to LOW and cooking until the frittata is just about set. You’ll need to allow around three and a half hours. Next, you’ll remove the lid and continue cooking. This will help the liquid on the top of the frittata to evaporate. Before serving, garnish with chopped fresh parsley.