Cook the pasta. Bring a large pot of water to a rapid boil, then season with a few tablespoons of Kosher salt. Add penne, stir, then cook until al dente, about 10 minutes. Before draining, reserve at least 1 cup of pasta water.
Cook the shrimp. Season the shrimp on both sides with 1 tsp Kosher salt and ¼ tsp black pepper. Heat 2 Tbsp (30ml) olive oil in a large skillet over medium-high heat. When hot, add shrimp and cook until they just turn pink on each side, about 2 minutes per side. Use tongs to remove shrimp to a cutting board, allow to cool slightly, then chop into bite size pieces. Set aside.
Sauté the onion. To the same skillet, add diced onion and cook 4-6 minutes over medium-high heat, until softened, stirring occasionally. Add chopped garlic, ¼ tsp crushed red pepper flakes, and remaining ¼ tsp Kosher salt, then cook 1 minute more.
Add tomatoes and vodka. Add 3 Tbsp tomato paste, then stir and cook until dissolved, about 1-2 minutes. Deglaze with 2oz vodka, then continue cooking about 2 minutes more.
Finish the sauce. Pour in a 15oz can of crushed tomatoes. Add ¾ cup (180ml) of heavy cream and the chopped shrimp. Stir until well mixed. Add the cooked pasta, ½ cup of reserved pasta water, and ½ cup grated Parm, stir until the cheese has melted and the sauce is luscious and creamy. Taste and adjust seasoning as needed, adding remaining pasta water if you want more of a sauce.
Garnish, then serve. Serve immediately with a drizzle of high quality extra-virgin olive oil, grated Parmesan, flaky sea salt, and lots of fresh basil!