In a large pot or Dutch oven, heat 2 tablespoons of olive oil over medium heat. Once hot, add the Italian sausage, breaking it apart with a wooden spoon. Cook until browned and cooked through, about 5-7 minutes.
Add the minced garlic to the pot with the sausage. If you like, sprinkle in the optional oregano for an added layer of flavor. Sauté for about 1-2 minutes until the garlic is fragrant.
Pour in the can of petite diced tomatoes, along with their juices, and add 2 cups of water. Stir everything together, scraping up any brown bits from the bottom of the pot.
Add the penne pasta to the pot, ensuring it is submerged in the liquid. Bring the mixture to a boil, then reduce the heat to a simmer. Cover the pot and let it cook for about 12-15 minutes, or until the pasta is al dente.
Once the pasta is cooked, remove the pot from the heat. Stir in the sour cream and freshly grated Parmesan cheese until well combined and creamy.
Gently fold in the chiffonaded fresh basil, reserving a small amount for garnish. Season with freshly ground black pepper to taste.
Spoon the pasta into bowls, garnishing with the reserved basil and additional Parmesan cheese if desired. Serve hot and enjoy!
