Preheat Oven and Coat:
Heat oven to 400°F (205°C). Coat a baking dish or sheet pan lightly with oil.Mix Chicken Filling:
In a large bowl, mix together shredded chicken, bacon, mozzarella, cheddar, ranch dressing, garlic powder, onion powder, and black pepper.Soften and Fill Tortillas:
Soften tortillas briefly to make them flexible. Divide chicken mixture evenly among tortillas and fold them.Place Tacos Seam Down:
Place tacos in the prepared dish with the seam facing down.Brush Tops with Oil:
Brush or spray the tops lightly with olive oil or melted butter.Bake Until Crispy:
Bake uncovered until tortillas are crispy and cheese has melted, 15–18 minutes.Top with Lettuce and Ranch:
Take out of the oven, then sprinkle shredded lettuce on top and add a drizzle of ranch dressing.Serve Immediately:
Serve right away.