01 -
Preheat the oven to 350°F with a rack in the center position. Line a rimmed sheet pan with foil.
02 -
In a large bowl, combine the ground beef, sausage, breadcrumbs, Parmesan, parsley, egg, garlic, salt, and pepper. Mix well to evenly combine.
03 -
With wet hands, form golf ball-sized meatballs (about 2 tablespoons each) and place them on the prepared sheet pan. You should have about 15 meatballs. Arrange them evenly on the pan.
04 -
Bake the meatballs in the preheated oven for about 25 minutes, or until browned and cooked through.
05 -
Meanwhile, in a small saucepan over medium heat, combine the butter and marinara sauce. Cook until the butter is melted and the marinara is warmed through, about 5 minutes.
06 -
Divide the meatballs and sauce among bowls. Sprinkle with additional Parmesan cheese and garnish with parsley, if desired.