Cook the penne according to package directions. Drain and set aside — the pasta should be al dente so it stays firm when baked.

In a large skillet, cook the Italian sausage and ground beef until fully browned. Break them up well so they mix evenly into the casserole. Drain excess fat to keep the dish from becoming heavy.

Add pepperoni slices directly into the skillet, followed by marinara sauce. Stir in the Italian seasoning and let the mixture simmer for a few minutes so the flavors meld together.

Fold the cooked pasta into the meat sauce, making sure every piece is coated with that rich, meaty goodness.

Transfer everything into a baking dish and sprinkle generously with mozzarella and Parmesan.

Bake at 375°F (190°C) for about 20 minutes, or until the cheese is melted, golden, and bubbling around the edges.

Let the casserole sit for 5 minutes before serving. Then enjoy each cheesy, meaty bite!