Melt butter in 12-inch skillet until sizzling; add chicken pieces.
Cook over medium-high heat until chicken is lightly browned (4 to 6 minutes).
Add mushrooms; continue cooking until chicken is no longer pink and mushrooms are tender (4 to 6 minutes). Do not drain.
Spread 1/2 cup sauce into greased 13x9-inch baking dish.
Arrange single layer of frozen cheese filled ravioli over sauce;
drizzle 3/4 cup sauce evenly over ravioli.
Spread with 1 1/2 cups chicken and mushroom mixture, 1/2 cup red bell pepper and half the mozzarella cheese.
Repeat with remaining ingredients, except remaining mozzarella cheese and Parmesan cheese.
Cover tightly with aluminum foil. Bake for 45 minutes. Remove foil; sprinkle with remaining mozzarella and Parmesan cheese. Bake, uncovered, for 15 to 20 minutes or until cheeses are melted. Let stand 15 minutes before serving.