- Preheat oven to 425°F (220°C). Bring salted water in a large pasta pot to a boil. While the water is coming to a boil, heat olive oil in a pan. Sauté onion and garlic in olive oil with chili flakes, sage, salt, and pepper to taste until onions are translucent. Set aside.
- Cook the pasta and squash in the same pot until tender. Measure out the pasta water, and then drain the pasta. Set the pasta and squash aside.
- In the pasta pot, mix the pasta water, milk, goat cheese, onion-garlic mixture, toasted walnuts (set 2 tbsp. aside for topping), bacon, and ⅓ cup of shredded cheese. Add the squash and pasta and toss together until well mixed.
- Transfer pasta mixture to a 9 x 9-in (2 L) baking dish. Top with the reserved walnuts and remaining cheese. Season with pepper. Bake for 20 minutes, or until top is golden brown.
Option: To garnish and add flavour, toss 4 to 5 whole small sage leaves with a 1 tsp. olive oil. Place on top of pasta before baking.