Chile Rellenos Casserole

1/2 pound lean ground beef
1 cup chopped onion
1 3/4 teaspoons ground cumin
1 1/2 teaspoons dried oregano
1/2 teaspoon garlic powder
1/4 teaspoon salt
1/4 teaspoon pepper
1 16 oz can fat-free refried beans
2 4 oz cans whole green chiles, drained and -- cut into quarters
1 cup (4 oz) pre-shredded Colby-Jack cheese -- divided
1 cup frozen whole kernel corn -- thawed and drained
1/3 cup all-purpose flour
1/4 teaspoon salt
1 1/3 cups skim milk
1/8 teaspoon hot sauce
2 large eggs -- lightly beaten
2 large egg whites -- lightly beaten
red onion slices -- (optional)
Cilantro sprigs -- (optional)

Preheat oven to 350

Cook ground beef (or turkey) and chopped onion in a nonstick skillet over medium-high heat until meat is browned, stirring to crumble. Remove from heat; add cumin and next 5 ingredients. Stir well; set aside.

Arrange half of green chiles in an 11 X 7-inch baking dish; top with 1/2 cup of cheese. Spoon mounds of beef mixture onto cheese; spread gently, leaving a 1/4-inch border around edge of dish.

Top with corn. Arrange remaining green chiles over corn; top with 1/2 cup cheese.

Combine flour and 1/4 teaspoon salt in a bowl; gradually add milk and next 3 ingredients, stirring with a whisk until blended. Pour over casserole.