- Bring 6 quarts of salted water to a boil in an 8-quart pot over high heat. 
- Pour tomatoes and their liquid into a food processor. Using quick on/off pulses, process until finely chopped (avoid over-processing to prevent turning pink). 
- Add penne to boiling water and cook semi-covered, stirring occasionally, for 8-10 minutes until al dente. 
- Meanwhile, heat olive oil in a large skillet over medium heat. Whack garlic cloves with the side of a knife and add to hot oil. 
- Cook garlic, shaking skillet, until lightly browned, about 3 minutes. 
- Carefully slide chopped tomatoes into the skillet. Bring to a boil, season with salt and crushed red pepper, and boil for 2 minutes. 
- Pour in vodka, reduce heat to a lively simmer, and cook until pasta is ready. 
- Just before pasta is done, remove garlic cloves from sauce and pour in cream. Add butter or oil if using, swirling to incorporate. 
- Transfer pasta directly to sauce using a wire skimmer, or drain pasta and return to pot with sauce. 
- Bring sauce and pasta to a boil, stirring to coat. Check seasoning and adjust as needed. 
- Sprinkle parsley over pasta and boil until sauce clings to pasta. 
- Remove from heat, add 3/4 cup cheese, and toss. Serve immediately with additional cheese.