Total time about 20 minutes. Vodka adds depth without tasting boozy; substitute chicken stock for alcohol-free, or deglaze with 1/2 cup dry white wine after the tomato paste. Regular or double-concentrate tomato paste both work in the same quantity. Grate the parmesan finely and avoid pre-grated, which can make the sauce grainy. Reserved starchy pasta water is essential to emulsify and loosen the sauce. Warm the serving bowls to keep the sauce silky.
