Preheat oven to 400 degrees. Lightly grease a 2-quart baking dish and set aside.
Line a baking sheet with foil and set aside.
In a large mixing bowl mix together butternut squash, a few drizzle of olive oil (enough to coat the squash), and a few dashes of salt and pepper. Mix well.
Spread the butternut squash over the baking sheet and roast in oven for 25 minutes turning once half way through.
Meanwhile cook pasta until al dente, drain, rinse with cold water and set aside.
In a medium saucepan heat 1 Tbsp. of butter on medium heat. Add sage leaves and gently stir until they begin to crisp (be careful not allow them to burn). Chop the sage leaves once done cooking and set aside on plate.
In the same medium saucepan on medium-high heat 1 Tbsp. butter. Add flour and milk and a dash of salt and pepper and whisk constantly until it turns into a thick and bubbly mixture. Remove from heat (make sure not to let it burn).
Remove the butternut squash from the oven and put in a large mixing bowl and mash gently with the back of the fork. Add the flour and milk mixture, pasta and sage leaves and stir.
In the 2 quart baking dish put half of the pasta mixture and sprinkle a layer of fontina cheese. Add remaining pasta mixture and another layer of cheese.
Bake in the oven uncovered for 20 minutes. Remove from oven and let sit for 5 minutes.
Serve pasta alongside crusty bread, a fresh fall vegetables and a side salad. Enjoy!