Blend the cashews: Drain the soaked cashews and blend them with the water until smooth. Set aside.
Cook the pasta: Cook the pasta according to the package instructions. Drain the pasta, reserving ½ cup (120 ml) of pasta water, and set both aside.
Sauté the onion and garlic: Heat the olive oil in a large skillet over medium heat. Add the onion and garlic, and cook until soft and fragrant, about 3-5 minutes.
Add tomato paste, salt, and pepper: Add the tomato paste, salt, and pepper, and stir to combine. Continue stirring for 2-3 minutes, until the paste turns a bright red color.
Deglaze with vodka: Pour in the vodka to deglaze the skillet, stirring until the vodka has evaporated.
Add pasta water: Add the reserved pasta water to the skillet and stir until smooth, about 1 minute.
Stir in the cashew cream: Add the cashew cream to the sauce and stir until the mixture is smooth. Lower the heat to medium-low and let it simmer for about 3 to 4 minutes.
Add vegan butter and Parmesan: Mix in the vegan butter and vegan Parmesan shreds, then simmer for another 3 minutes until the sauce becomes smooth, glossy, and thick enough to coat the back of a spoon.
Combine pasta and sauce: Add the cooked pasta to the sauce and toss until the pasta is completely coated. Taste and add more salt or pepper if needed.
Serve: Serve immediately with more vegan Parmesan shreds if desired.