Adapted from here.
Meanwhile, warm olive oil in a large, heavy bottomed pot over medium heat. Add pancetta and cook, stirring occasionally until crispy (4 to 5 minutes). Stir in onion, garlic and red pepper flakes, and cook, stirring occasionally until the onion is translucent (about 4 minutes).
Add tomato paste and cook, stirring often, until it takes on a deeper shade of red and starts to brown on the bottom of the pot (6 to 7 minutes). Deglaze the pan with the vodka, scraping up any bits that may be stuck on the bottom of the pot. Reduce heat to low, then slowly stir in the heavy cream to form a smooth sauce. Season to taste with salt and black pepper.