Place an oven rack about 5 inches from broiler and preheat broiler to high. Toast tortillas under broiler, turning once, until lightly spotted, 2 to 3 minutes total. Reserve 2 Tbsp. enchilada sauce. Combine beans and remaining sauce in a bowl.
Mist slow-cooker insert with cooking spray. Place 3 tortillas in bottom, breaking one into pieces if necessary to cover bottom. Spread half of bean mixture over tortillas. Sprinkle with 1 cup corn and 1/2 cup cheese. Repeat with 3 more tortillas, remaining bean mixture, remaining corn and 1 cup cheese. Top with 3 remaining tortillas, reserved sauce and remaining 1 cup cheese. Cover and cook on low until cheese has melted and is beginning to crisp on edges, 2 to 3 hours.