In a 2-quart glass baking dish, place 6 muffin halves. In a medium bowl, combine cheese, ham, peppers, and onion. Sprinkle half of cheese mixture over muffin halves. In a 4-cup glass measure, beat together eggs and milk and chili powder (or other seasoning as desired). Pour half of mixture over muffins in dish. Repeat layers with 6 remaining muffin halves and remaining cheese mixture and milk mixtures, pressing muffins down into liquid. Cover with plastic wrap and refridgerate overnight. Remove dish 30 minutes to an hour before baking. Remove the plastic wrap and cover with wax paper. Microwave on High 5 minutes; rotate dish. Microwave on Medium-High (70%), 5 to 7 minutes, or until knife inserted one inch from center comes out clean. Uncover, let stand 10 minutes before serving.