Preheat the oven to 425 F. Brush an 18×13-inch sheet pan with melted butter or cooking spray
In a bowl, mix together the shredded chicken, bbq sauce, & most of the diced onion
Add 6 of the tortillas around the edges of the sheet pan, hanging halfway over the edge of the pan. Place 1 tortilla in the bottom to cover the open space
Evenly spread the chicken mixture over the tortillas. Sprinkle the rest of cheese evenly over the chicken mixture
Place the last tortilla in the center of the mixture. Fold the tortillas that are hanging over the edge of the pan. Place a second sheet pan on top of the tortillas and press down
Add to the oven and bake for 20-25 minutes
Remove from the oven and allow a few minutes to cool before slicing
Add toppings and enjoy
