Butternut Squash Pasta

Bahan-bahan (4 porsi)

• 1 large head garlic
• 1 medium butternut squash (2 pound to 2 1/2 pounds)
• 1 small onion
• 3 tablespoon extra-virgin olive oil (divided)
• 1 teaspoon kosher salt (plus extra for cooking the pasta)
• 1/2 cup low-fat milk ((I used 1%), plus additional as needed)
• 1 pound whole wheat rotini pasta (or similar short, twisty, tubular pasta such as cavatappi, penne, or fusilli)
• 2 tablespoons unsalted butter
• 1 tablespoon finely chopped fresh sage (plus additional for serving)
• 4 ounces gouda cheese (shredded (about 1 cup))
• 1/4 teaspoon crushed red pepper flakes
• 1/4 cup finely grated Parmesan cheese (about 1 ounce, optional)