For garnish: fresh basil, crushed red pepper flakes, and grated Parmesan cheese
Preheat oven to 425 degrees Line a large sheet pan with aluminum foil and spray with nonstick spray. Set aside.
Remove the gnocchi from the package and make sure none of the gnocchi are stuck together. Spread the gnocchi, sausage, peppers, and onions on the baking sheet. Pour marinara sauce over the gnocchi, sausage, and vegetables. Toss until well coated in the sauce. Note-you can also do this in a bowl before putting on the pan, but I don’t like to dirty an extra dish, I combine right on the pan.
Spread the gnocchi, sausage, and vegetables in an even layer on the sheet pan.
Place the pan in the oven and bake for 20 minutes, tossing once halfway through. Remove the pan from the oven and evenly sprinkle fresh mozzarella cheese cubes over the top. Place the pan back in the oven and bake until cheese is melted, about 5 minutes.
Remove the pan from the oven. Garnish with fresh basil, crushed red pepper flakes, and grated Parmesan cheese. Divide the gnocchi onto plates or bowls and serve immediately.