Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray.
Add onion; saut 2 minutes.
Add jalapeo; saut 2 minutes.
Sprinkle sugar over onion mixture; saut 1 minute.
Remove onion mixture from pan.
Return pan to heat; recoat with cooking spray.
Add mushrooms and garlic to pan; saut 1 minute.
Add Madeira to pan; cover, reduce heat, and simmer 2 minutes. Uncover; cook 2 minutes or until liquid evaporates, stirring frequently. Stir in onion mixture and chicken; cook 3 minutes or until thoroughly heated.
Warm tortillas according to package instructions. Spoon about 1/3 cup chicken mixture onto each tortilla. Top each tortilla with 2 tablespoons cheese; fold in half.