Heat oven to 375°F. With top edge of custard cup as a pattern, cut out round from each cheese slice. In each round, cut out small triangles for eyes and nose, and small shape for mouth to resemble jack-o'-lantern. Set aside. Spray outside bottom and sides of eight 6-ounce custard cups lightly with cooking spray.
Separate dough into 8 biscuits. Roll or pat each biscuit into 4 1/2-inch round. Place biscuit rounds over outside of sprayed cups; press to fit over bottom and part way down sides of cups. Place cups, upside down, in ungreased 15x10-inch pan with sides.
Bake 15 to 20 minutes or until deep golden brown.
Meanwhile, in medium saucepan, cook taco sauce with chicken, corn and chiles over medium heat 10 to 15 minutes, stirring occasionally, until mixture is thoroughly heated. Stir in sour cream. Cook 3 to 5 minutes, stirring frequently, just until thoroughly heated.
Remove pan from oven. Carefully remove biscuit cups from custard cups; place biscuit cups, right side up, in same baking pan. Spoon chicken mixture evenly into each biscuit cup. Top each with tomato slice and jack-o'-lantern cheese slice.
Return to oven; bake 2 to 4 minutes longer or until cheese is melted. Sprinkle tops of cheese with shredded lettuce to resemble hair.