In this incredibly easy weeknight pasta, red-pepper flakes, capers and tomato paste turn a simple cherry tomato sauce into something hearty enough for cold weather. Sautéeing tomato paste until it caramelizes develops deep flavor, while pan-fried capers add crunch and red-pepper flakes provide heat. For smokier undertones, you can use dried ancho chile or chile de árbol, chipotle powder or Aleppo pepper in place of the red-pepper flakes. A dollop of ricotta, freshly grated pecorino or Parmesan, or shaved ricotta salata is not necessary, but takes the dish up a notch.
