Cook the penne pasta according to package instructions until al dente.
In a large skillet, heat a drizzle of olive oil over medium heat.
Add the Italian sausage to the skillet, breaking it apart with a wooden spoon.
Once the sausage is browned, stir in the onion and bell peppers.
Add the minced garlic and cook until fragrant, about 1 minute.
Pour in the diced tomatoes, oregano, and red pepper flakes, stirring everything together.
Season with salt and pepper, and let the mixture simmer for about 10 minutes.
Drain the cooked pasta and add it directly to the skillet, tossing gently.
Stir in fresh basil just before serving for a burst of freshness.