Preheat oven to 375°F. Spray 12 regular-size muffin cups with cooking spray.
In 10-inch nonstick skillet, heat oil over medium-high heat. Cook chicken in oil 5 to 7 minutes, stirring occasionally. Add onion and chicken broth; heat to simmering. Add frozen vegetables and seasonings. Heat an additional 3- 5 minutes, stirring occasionally until almost all liquid is absorbed. Cool 5 minutes; stir in cheese.
In medium bowl, stir baking mixture ingredients with whisk or fork until blended. Spoon 1 scant tablespoon baking mixture into each muffin cup. Top with about 1/4 cup chicken mixture. Spoon 1 tablespoon baking mixture onto chicken mixture in each muffin cup.
Bake 25 to 30 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes. With thin knife, loosen sides of pies from pan; remove from pan and place top sides up on cooling rack. Cool 10 minutes longer, and serve.