01 -  Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish or large ovenproof skillet using melted butter or nonstick spray. 
 02 -  Evenly distribute the quartered biscuit dough pieces across the base of the prepared dish. 
 03 -  In a large bowl, whisk together eggs, whole milk, salt, black pepper, and optional smoked paprika until fully incorporated. 
 04 -  Stir in shredded cheddar, mozzarella, and Parmesan cheeses along with bell pepper, onion, baby spinach, and any optional cooked sausage or bacon. 
 05 -  Pour the egg mixture evenly over the arranged biscuit pieces. Use a spatula to gently press down so biscuits are mostly submerged. 
 06 -  Drizzle the melted butter over the top for enhanced flavor and browning. 
 07 -  Bake for 25 to 30 minutes, until the frittata is puffed and the center is set. 
 08 -  Let rest for 5 minutes before slicing. Sprinkle with chopped fresh parsley, if desired.