Bring a large pot of water to a boil and cook pasta according to package instructions.
Add the cashews to a bowl and cover with boiling water.
Mince the garlic, chop the onion, and add to a sauté pan with 2 tbsp of the olive oil.
Sauté until lightly golden brown, about 5 to 10 minutes over medium/low heat.
Reduce heat to low, pour in the vodka and let simmer for about 3 minutes.
Transfer to a blender or food processor. Add in the drained and rinsed cashews, the rest of the olive oil, and all remaining ingredients except for the basil.
Process until completely smooth.
Taste and adjust seasonings as desired.
Pour the sauce back into the sauté pan. If using the parmesan cheese, stir it in and let it cook for a couple of minutes.
Combine with the cooked pasta and stir until well incorporated.
Top with fresh basil and enjoy.