To make this Italian Rigatoni Bake gluten free, replace the regular rigatoni with certified gluten-free rigatoni or another sturdy gluten-free pasta shape. Cook the gluten-free pasta just until al dente, as it can soften more quickly during baking. Confirm that the Italian sausage, tomato sauce, diced tomatoes, cheeses, Italian seasoning, red pepper flakes, and dried basil are certified gluten free or processed without gluten cross-contamination. Use a gluten-free cooking spray or plain oil for greasing the baking dish.