In a mixing bowl, whisk together the hot sauce, melted butter, and garlic powder. Add the shredded chicken and toss until evenly coated. Fold in the cream cheese pieces and blue cheese crumbles if using. The cream cheese should be in small pockets throughout, not fully blended.

Heat a large skillet over medium heat. Brush one side of a tortilla lightly with oil and place it oiled-side down in the pan. Sprinkle 0.5 cup of Monterey Jack over half the tortilla, leaving a 0.5-inch border. Top with about 0.5 cup of the buffalo chicken mixture and drizzle with 1 tablespoon ranch. Fold the empty half over to create a half-moon.

Cook for 3-4 minutes until the bottom is golden brown and crisp. Carefully flip with a spatula and cook another 2-3 minutes until the second side is browned and the cheese is fully melted. Transfer to a cutting board and let rest for 1 minute before cutting into wedges. Repeat with remaining tortillas.

Cut each quesadilla into 3 wedges. Serve hot with extra ranch dressing and hot sauce on the side for dipping.