Preheat the oven to 425°F

Place the squash in a 13x9 baking pan along with the 2T of cubed butter and whole garlic cloves.

Sprinkle with salt. Roast for 25 minutes, or until squash is soft when pierced with a fork. Reduce oven temperature to 375°F.

Purée contents of baking pan until smooth.

Heat remaining 4T butter in a large saucepan. Add milk, salt, and butternut purée. Whisk ingredients until smooth, then cook on medium-low heat until slightly thickened.

Place cooked pasta into the 13x9 baking pan, and pour the cheese sauce over it. Mix the cheese sauce into the noodles until thoroughly combined.

Once thickened, add cheeses.

Bake uncovered until the cheese bubbles, about 20 minutes.