Lasaña de pure de calabaza

Ingredients

• 1 box Banza Lasagna
• 4 tablespoons extra-virgin olive oil, divided, plus more for drizzling
• 1 large onion, finely chopped
• 3 garlic cloves, thinly sliced
• 1/2 teaspoon crushed red pepper flakes
• 1 small butternut squash, peeled, halved, seeded, cut into 1/2 in. cubes (about 6 cups)
• 4 cups chicken or vegetable stock
• 1 1/2 cups Parmesan, finely grated, plus more for serving
• 1/2 cup walnuts
• 1 cup basil leaves, torn
• Freshly ground black pepper