Start a large pot of water to boil and measure out the pasta. Take a moment to open up the canned whole tomatoes and pour into a strainer set over a bowl, to drain off the excess liquid. Set aside.
In a large skillet, melt the butter over medium heat. Add the onion and stir to combine. Reduce heat to low and loosely lay a sheet of aluminum foil over the onions. Allow to cook over low heat for 8-10 minutes. (The goal is to really soften the onion, but to not allow them to brown. The foil keeps the moisture in the pan, which will prevent browning).
When pasta water is boiling, generously salt the water and add the pasta. Cook until al dente.
Remove the foil and add the garlic to the pan. Increase the heat under the pan to medium. Cook the garlic, stirring about 30-45 seconds (don't let the garlic brown at all), the add the Calabrian chili paste and tomato paste to the skillet. Cook, stirring, about 2 minutes, or until the tomato paste darkens slightly. Hand crush the whole tomatoes you are draining, then add to the skillet. Stir to combine. Season with a generous pinch of salt and a bit of freshly ground pepper. Reduce heat to low and allow the sauce to continue heating until the pasta is ready.
When the pasta is almost ready, remove the sauce to a blender. Remove the top stopper from the blender to allow the steam to escape and cover the top with a tea towel before blending. Pulse or blend until smooth. Alternately, transfer sauce to a deep bowl and use am immersion blender to puree. Use a deep bowl and stand back a bit, as the hot sauce can splatter a bit.
Return the pureed sauce to the skillet, and heat briefly over medium heat. Add the vodka and stir in. Allow the vodka to cook off in the sauce for 1-2 minutes.
*Remove and reserve about 1 cup of the pasta water, to use in the sauce, if necessary. Add the cooked pasta to the sauce and stir to combine. Cook the pasta with the sauce for 1 minute, then add the basil, drizzle of cream and Parmesan. Stir to combine. *If necessary, you can add a splash of pasta cooking water, if the sauce gets too thick and you need to loosen. I don't often find it needs it. Taste sauce and add additional salt, as needed (I usually find I need to add salt to really bring all the great flavours together.)
Serve garnished with additional Parmesan cheese and chopped fresh basil.
1. When it comes to adding spiciness to a dish, it's always a good idea to start small and go from there. 1 tsp of Calabrian Chili Paste will produce a pleasant amount of spice, certainly enough to qualify it as a "spicy" pasta. 2 teaspoons will produce a definitely spicy, warm dish, but not a "pass the milk/my mouth is burning" level of heat. I can eat it with 2 tsp and I'm a bit of a spice lightweight. That said, the sweet spot for me (the spice lightweight) is probably in the 1 - 1 1/2 tsp range. Again, especially if you are unsure, start with a bit (1/2 tsp), taste and add more until you get to your preferred spice level.If you don't have Calabrian Chili Paste, you can simply use dried red pepper flakes, or you can try the DIY chili paste recipe below.Homemade Substitute for the Calabrian Chili Paste:If you want to try a bit of a DIY spicy paste, using just a few easy, common ingredients, you can give this a try. It doesn't taste exactly like the Calabrian chili paste, which is difficult to duplicate without Calabrian chilis, but it will be a little more complex in flavour than just the red pepper flakes on their own. Don't worry if you don't exactly all the ingredients. Just mixing the oil, red pepper flakes, tomato paste and vinegar is fine.1 tsp neutral oil or olive oil 1 1/2 tsp dried red pepper flakes 1 tsp tomato paste 1/4 tsp lemon zest 1/8 tsp red wine vinegar Tiny pinch of smoked paprika Pinch of saltStir together and let stand 30-60 minutes before using or refrigerate until needed. This mix isn't as spicy as the Calabrian, but the red pepper flakes will still be spicy, so add a little to start and go from there.2. Note that it is 14 oz and not the typical, large 28 oz can of tomatoes. Whole tomatoes are generally available in the smaller can size (Mutti makes a great one). If you only have 28 oz cans, just use 1/2 the can and freeze the rest. You can also freeze any left-over tomato paste.3. The amount of cream you add is totally up to you. I prefer not too much, as I find too much cream drowns out the lovely tomato flavours we've built in our sauce and frankly, it's just too rich for me. I do a "drizzle" myself, which probably equals about 2 Tbsp. I suggest starting there. You can can always add more, if you like it creamier.