1 tablespoon unsalted butter 1/2 cup chopped yellow onions 1 cl pressed 8 ounces white mushrooms, sliced 1 pound boneless, skinless chicken breasts or thighs, cooked and cubed (i use a prepared rotisserie chicken) 2 cups broccoli florets, steamed 1 cup alfredo sauce, homemade (here) or store-bought 1/2 cup shaved parme