Heat oven to 375ºF. Line 15x10x1-inch pan with foil. Place 2 (10-oz) custard cups upside down in pan. Brush outsides of cups with 1 teaspoon of the oil.
Brush one side of tortillas with remaining 1 teaspoon oil; place tortillas over cups, oil side up. Bake 8 to 10 minutes or until light golden (tortillas will soften and drape over cups as they bake). Carefully remove tortillas from custard cups; turn tortilla cups over. Cool 2 minutes.
In medium microwavable bowl, place taco sauce with shredded chicken. Cover and microwave on High 2 to 4 minutes, stirring halfway through, until hot. Stir in corn, tomatoes and enchilada sauce. Microwave on High 1 to 2 minutes or until warm. Spoon warm mixture evenly into baked tortilla cups. Top each with cheese and onions.