Cut chicken breasts in large cubes, roll in flour and lightly brown in butter. Remove chicken and cook onions in the same pan until transparent. Add bouillon, broth, sugar and mushrooms. Bring to slow boil and cook 5 minutes. Add remaining 4 ounce cheese and cook until cheese is melted. Add sour cream and blend well.

Place the chicken pieces over the tortellini in pan. Pour sauce over the chicken and cover with foil. Bake 40 minutes at 275-300 degrees.