Preheat oven to 350 degrees F and bring large pot of salted water to boil.

Once boiling, drop in pasta and cook 4 minutes less than box instructions.

While pasta cooks, heat pot over medium-high heat and toss in cubed pancetta. Cook until fat renders and pancetta browns.

Remove pancetta and set aside in bowl. Pour out excess fat, leaving about 1 tablespoon in pot. Add 1/2 tablespoon olive oil, lower heat slightly, add cut sage, and fry a few seconds until crunchy. Remove and set aside with pancetta.

Add garlic and rosemary to pot; cook until fragrant. Add cubed butternut squash and salt; cook a few minutes.

Add 1/4 cup water, cover with lid and steam until squash is fork-tender (5–10 minutes).

Use immersion blender to purée squash into paste. Stir in cream, fontina, pancetta and sage until evenly combined.

Add cooked pasta and mix to coat in sauce. Pour into 9x13-inch baking dish and top with grated Parmigiano Reggiano.

Bake 30 minutes, then broil 5 minutes or until top is golden and crisp. Serve hot or reheat next day.