reheat oven to 425°F. Grease one 18×13-inch baking sheet. Lay 6 tortillas across the sheet with edges hanging over.
Heat oil in a skillet. Sauté ½ cup onion and 2 cups peppers for 3–5 minutes. Stir in 2 cups chicken, 1 cup black beans, and ½ cup salsa. Cook 2 minutes.
Spread filling over tortillas. Top with 2 cups cheese. Place 1–2 tortillas in center to cover gaps. Fold overhangs to seal.
Lightly spray top. Place second 18×13-inch baking sheet on top to press. Bake 20 minutes until golden and crisp.
Rest 5 minutes. Slice and serve with salsa, sour cream, or guacamole.
Recipe Notes:
Use two sheet pans for the crispiest finish.
Let it rest before slicing to keep fillings in place.