Cook the penne pasta according to package directions. Drain, reserving about 1 cup of pasta water.
While the pasta is cooking, heat the olive oil in a large skillet over medium heat. Add the chopped onion and cook until softened, about 5-7 minutes.
Add the minced garlic and cook for another minute until fragrant.
Pour in the vodka and let it simmer and reduce by half, about 3-5 minutes. This helps to cook off the alcohol.
Stir in the crushed tomatoes and bring to a simmer. Cook for about 10 minutes, stirring occasionally.
Reduce the heat to low and stir in the heavy cream and grated Parmesan cheese. Cook until the sauce is heated through and slightly thickened, about 5 minutes. Do not boil.
Season the sauce with salt and black pepper to taste.
Add the cooked penne pasta to the sauce and toss to coat. If the sauce is too thick, add a little of the reserved pasta water until it reaches your desired consistency.
Serve immediately, garnished with fresh basil.
Notes
For an extra kick, you can add a pinch of red pepper flakes to the sauce along with the crushed tomatoes.