Bring a large pot of salted water to boil and cook penne pasta according to package directions until al dente. Reserve 1 cup pasta water before draining.

While pasta cooks, heat olive oil in a large skillet over medium heat. Add diced onion and cook for 3-4 minutes until softened.

Add minced garlic and cook for 1 minute until fragrant, being careful not to burn.

Stir in tomato paste and cook for 2-3 minutes, stirring constantly to develop deep flavor.

Carefully pour in vodka and simmer for 2-3 minutes to cook off alcohol, stirring occasionally.

Reduce heat to low and slowly add heavy cream, stirring constantly to create smooth sauce.

Add red pepper flakes, salt, and pepper. Simmer for 5 minutes until sauce thickens slightly.

Add cooked pasta and butter, tossing to coat. Add pasta water as needed for consistency.

Remove from heat and stir in fresh basil and half the Parmesan until melted.

Serve immediately topped with remaining Parmesan and fresh basil garnish.