Bring a large pot of water to a boil and season generously with salt
Cook the pasta until it's very al dente (it will finish cooking in the sauce so you want it to be underdone), reserve ½ cup of pasta water then drain
Melt 1 tbsp of the butter in a large sauté pan over medium-low heat until it stops foaming, then add the olive oil
Add the shallot and season with salt so it doesn't burn, then sauté for 2-3 minutes until softened
Add the chili flakes and garlic and sauté for an additional minute or until the oil starts to darken from the chili flakes and the garlic is fragrant
Add the vodka and scrape to deglaze the pan, then cook for 30 seconds or until it has mostly reduced
Reduce the heat to low; pour in the cream then add the salt and Parmesan cheese
Stir and simmer over low heat until the sauce starts to thicken
Add the pasta and mix, then add pasta water 1 tbsp at a time until the sauce is silky and creamy and sticks to the pasta (see Note 4)
Stir in the remaining tbsp of butter (if you find your sauce is already creamy enough, you can skip it)
Taste and season with additional salt if required (the pasta water is salty so don't add more salt until after you've added the pasta water)
Serve topped with extra Parmesan cheese, fresh parsley and freshly cracked black pepper, if desired