Preheat the oven to 375°F. Bring a large pot of salted water to a boil. Cook the Potato Gnocchi for 1 minute, then drain. In a large bowl combine the Marinara sauce and the Gnocchi.
Put a layer of Potato Gnocchi in a 9 x 13-inch casserole dish (approximately half of the quantity), then top with half of the mozzarella slices, grated Parmigiano Reggiano cheese and a few basil leaves.
Repeat with another layer of Gnocchi, the remaining mozzarella slices and grated Parmigiano Reggiano cheese. Bake until bubbly, 10-15 minutes. Garnish with additional basil leaves.