Preheat oven to 350 degrees.
Heat olive oil in skillet over medium heat. Add diced onions and garlic and cook for 2-3 minutes.
Add diced mushrooms and cook until they are softened, about 3 minutes.
Add ground turkey, Italian seasoning, salt, pepper and cook until done. Drain excess liquid if desired.
Sprinkle flour over meat mixture and stir.
Add chicken broth to meat mixture and set burner on medium heat.
Break spaghetti noodles in half, then add into skillet and allow to cook until noodles are al dente and there is minimal liquid remaining.
Slowly pour in half and half, and mix well.
Sprinkle freshly grated parmesan over mixture and stir until combined.
Transfer to a 9x13 pan and spread evenly.
Melt butter. Add breadcrumbs to melted butter and stir.
Sprinkle breadcrumbs evenly on top of the noodle and meat mixture.
Bake for 20 minutes, or until it's warm.
Allow to sit for 5 minutes before serving.