In a large skillet, heat a tablespoon of olive oil over medium-high heat. Add the Italian sausage, breaking it up with a spatula. Brown the sausage for about 5-7 minutes until caramelized and cooked through. Remove sausage from skillet and set aside.

In the same skillet, add another splash of olive oil if needed. Toss in the chopped onion and minced garlic, sauté for 2-3 minutes until the onion becomes translucent and fragrant.

Add the sliced red and yellow bell peppers to the skillet. Sauté for about 3-4 minutes until softened but still crunchy.

Sprinkle in the dried oregano and optional red pepper flakes, allowing them to toast for about 1 minute.

Pour in the chicken or vegetable broth and diced tomatoes, stirring well. Bring to a gentle simmer for 2-3 minutes.

Add the uncooked penne or rigatoni directly to the skillet, ensuring they are submerged. Cover and let simmer for 10-12 minutes, stirring occasionally until pasta is al dente.

Return the sautéed sausage to the skillet, mixing it in to reheat. Season with salt and pepper, then stir in the grated Parmesan cheese until melted.

Remove from heat and sprinkle fresh basil or parsley on top. Serve directly from the pan.