Quick Squash Lasagna

Ingredients

• 2¾ cups tomato purée or crushed canned tomatoes
• 2 tablespoons extra-virgin olive oil
• Flaky salt and freshly ground black pepper
• 2 garlic cloves, peeled and chopped
• Pinch of crushed red pepper flakes
• Two 15-ounce cans green or Puy lentils, drained (or 9 ounces home-cooked)
• ½ a butternut squash (about 1⅓ pounds), peeled and grated
• ⅓ cup black olives, pitted and chopped
• 2 tablespoons capers
• Zest of 1 lemon
• Small bunch of basil, leaves picked
• Two 4-ounce balls mozzarella or vegan-style mozzarella
• 9 ounces dried lasagna sheets