Bring a large pot of water to a rapid boil, then season with about 3-4 Tbsp of Kosher salt. Add penne, stir, then cook until al dente.
Season the shrimp on both sides with Kosher salt and black pepper. Heat EVOO in a large skillet over medium-high heat. Use tongs to remove shrimp to a cutting board, allow to cool slightly, then chop into bite size pieces.
To the same skillet, add diced onion and cook over medium-high heat, until softened, stirring occasionally. Add chopped garlic, crushed red pepper flakes, and remaining Kosher salt.
Add 3 Tbsp tomato paste, then stir and cook until dissolved. Deglaze with 2 oz vodka, then continue cooking.
Add ¾ cup of heavy cream and the chopped shrimp. Stir until well mixed. Taste and adjust seasoning as needed, adding remaining pasta water if you want more of a sauce.
Serve immediately with a drizzle of high quality EVOO, extra grated Parmesan, a pinch of flaky sea salt.