Preheat oven to 375°F (190°C).
In a skillet, cook the ground beef or sausage over medium heat until browned. Drain the grease.
In a bowl, mix ricotta or cottage cheese, sour cream, garlic powder, and a pinch of salt.
Spread a layer of marinara sauce in a 9x13 baking dish.
Add half of the frozen ravioli in a single layer.
Spoon half of the cheese mixture over the ravioli.
Sprinkle with half the mozzarella and part of the Parmesan cheese.
Add half the meat and sauce mixture.
Repeat all layers: ravioli, cheese mixture, mozzarella, Parmesan, meat sauce.
Finish with remaining mozzarella and Parmesan. Sprinkle Italian seasoning on top.
Cover with foil and bake for 30 minutes.
Uncover and bake another 15 minutes, until the cheese is golden and bubbly.
Let the casserole rest for 10 minutes before slicing.
Garnish with fresh basil or parsley if desired.