01 -
Fill a large pot with water and season generously with salt. Bring to a rolling boil, add rigatoni, and stir. Cook for 9 to 10 minutes until al dente. Reserve 120 ml of pasta water, then drain the pasta.
02 -
Heat olive oil in a wide deep pot over medium heat. Add chopped onion and crushed red pepper flakes if using. Sauté gently for about 10 minutes, stirring often, until onion is soft and golden but not browned.
03 -
Add Italian sausage to the pot, breaking it up with a wooden spoon. Cook without stirring for 2 minutes to develop color, then continue stirring until sausage is fully crumbled and browned with no pink remaining.
04 -
Add minced garlic, stirring constantly for about 1 minute until fragrant. Stir in tomato paste and cook for 1 to 2 minutes until the color deepens.
05 -
Pour grape tomatoes, white wine or chicken broth, salt, and pepper into the pot. Stir and gently press tomatoes against the pot to encourage bursting. Simmer for 10 minutes to release juices and develop flavor.
06 -
Stir diced zucchini into the sauce. Cook for 5 minutes until zucchini is tender yet firm and vibrant in color.
07 -
Add drained rigatoni to the pot with the sauce and vegetables. If sauce is too thick, add reserved pasta water a splash at a time. Toss thoroughly to coat pasta evenly.
08 -
Remove from heat and stir in chopped fresh basil. Divide into serving plates and top each with a generous amount of freshly grated Parmesan cheese before serving.