Preheat the oven to 375°F.

Coat a 2-quart casserole dish with olive oil spray and set aside.

Heat butter in a large skillet over medium high heat.

Add shallots, mushrooms and 1/4 teaspoon of salt and cook until softened and fragrant, stirring occasionally, for 7 to 8 minutes.

Transfer to a large bowl and set aside.

Bring a large pot of salted water to a boil and cook pasta according to package directions.

Drain, then transfer to bowl with mushroom mixture and set aside.

Heat oil in a saucepan over medium heat.

Whisk in flour until smooth, then whisk in broth and cook, stirring constantly, until thickened, about 3 minutes.

Stir in milk, sherry, nutmeg, the remaining 1/2 teaspoon salt and pepper and cook for 1 minute more.

Add to bowl with pasta and mushroom mixture; add turkey and toss well.

Transfer to prepared dish, then sprinkle with cheese and bake until hot and bubbly, about 30 minutes.