1. Bring a pot of generously salted water to a boil for the pasta.
2. In a large pan over medium-low heat, melt 2 Tbsp butter then add the onions. Season with 1/4 tsp kosher salt and 1/4 tsp pepper and cook, stirring often, until the onions are tender, golden, and caramelized, about 20 mins. Remove the onions from the pan and set aside.
3. Turn the heat to medium and add the remaining 2 Tbsp butter and the garlic. Cook while stirring for 1 min until fragrant. Add the San Marzano tomatoes with their juice, squeezing them with your hands as you put them in. Add the chopped calabrian chilis (start with 1 tbsp and add more to taste), sugar, 1 tsp more kosher salt, and vodka. Mix, breaking up any large tomato chunks into smaller pieces with your spatula.
4. Bring to a simmer over medium-high heat. Once the sauce starts bubbling, cover and simmer on low heat for 15 mins. Uncover and stir in the cream and caramelized onions, then cover and turn off the heat until the pasta is ready.
NOTE: Recipe instructions are continued in the comments of the original post and are not fully available here.
