Pre-heat oven to 350 degrees and spray a 9 x 13 baking pan with cooking spray.
Cook pasta according to package directions and set aside.
Heat butter in a large skillet over medium heat until melted. Stir in onion and 1 teaspoon of the salt. Cook until softened, 3-4 minutes before adding mushrooms. Continue cooking until mushrooms are soft, 3-4 additional minutes.
Sprinkle flour into the pan and stir for 30-60 seconds or until flour is absorbed into the pan. Pour in chicken broth and bring to a boil. Reduce heat to low and simmer until sauce thickens, 7-9 minutes.
In a large bowl, toss together cooked pasta with diced turkey, plain yogurt, remaining 1 teaspoon salt, half of the cheese (1 cup), lemon juice, Worcestershire sauce and pepper. Add in reduced mushroom sauce to the bowl and stir again.
Pour pasta mixture into the prepared baking dish and spread in an even layer. Sprinkle remaining cheese on top and bake until golden brown and bubbly, about 45-50 minutes. Let rest 5-10 minutes before serving to let the casserole settle.