Preheat the oven to 425°F (220°C) and spray a large rimmed baking sheet with cooking spray.
In a large bowl, beat the softened cream cheese, Buffalo wing sauce, and 2 tablespoons ranch dressing with a hand-held electric mixer until smooth.
Stir in the shredded cooked chicken, shredded cheddar or Colby Jack, blue cheese crumbles, and half of the sliced green onions. Season with black pepper to taste.
Place tortillas on a microwave-safe plate, cover with a damp paper towel, and microwave for about 40 seconds until pliable.
Divide the chicken mixture among the tortillas, placing it on the lower third of each tortilla, then roll up tightly and place seam-side down on the prepared baking sheet.
Lightly spray the tops of the taquitos with cooking spray and bake for 15 minutes, or until golden brown and crispy.
Transfer to a serving plate, sprinkle with the remaining sliced green onions, and drizzle with or serve alongside ranch dressing for dipping.