Preheat oven to 400˚F.
Halve and seed squash, then brush flesh side with oil.
Season with salt and pepper.
Place on parchment paper-lined baking sheet and bake cut side down for 35 to 40 minutes or until tender.
Meanwhile, cook pasta according to package directions; drain and reserve 1/4 cup pasta water.
Meanwhile, melt butter in large skillet set over medium heat.
Cook turkey, shallots, garlic and sage for 5 to 8 minutes or until starts to brown.
Sprinkle in flour, then continue to cook for 2 to 3 minutes or until smooth.
Slowly whisk in milk and bring to a boil.
Reduce heat to medium-low.
Cook, stirring constantly, for 8 to 10 minutes or until thickened.
Stir in salt and pepper.
Reduce heat to low and stir in cheddar cheese until melted.
Toss in pasta and pasta water.
Spoon mac and cheese into centre of each roasted squash half.
Sprinkle with parmesan cheese.
Reduce oven temperature to 350˚F.
Bake for 15 to 20 minutes or until golden brown and bubbly.