Puttanesca Sauce: Heat 2 tablespoons oil in a medium pot over low heat. Add garlic and anchovies; cook, stirring frequently to break up anchovies, until garlic is soft but not browned, 3-4 minutes. Add red pepper flakes; cook until fragrant, about 20 seconds. Add tomato purée, increase heat to medium, and cook, stirring occasionally, until sauce thickens, 15-20 minutes. Stir in olives; simmer for 5 minutes. Season with salt and pepper.