Cook the penne pasta to al dente. Meanwhile, cook diced boneless skinless chicken breast pieces and sliced button mushrooms in a hot skillet with a bit of olive oil. Let cook on high heat for a few minutes, stirring frequently. Once the chicken is done, stir in 2 heaping tablespoons of sour cream. When the pasta is cooked, add it to the creamy chicken skillet. Mix well to combine, and serve with a bit of grated Parmesan and parsley to garnish.