Prepare the Cheese Sauce by adding all the cheese sauce ingredients except the water to a food processor or blender. Blend until creamy, adding water as necessary to reach your desired consistency, then set aside.
Heat a large pan over medium heat and add the frozen onions and peppers to cook for about 4-5 minutes until thawed.
Once the vegetables are softened, stir in the pulled chicken, black beans, and corn into the pan. Cook for an additional 2-3 minutes until everything is heated through.
After removing the pan from heat, fold in the pre-prepared cheese sauce with the chicken mixture thoroughly.
Take approximately 8 ounces of the cheesy chicken mixture and add it to each tortilla before tightly rolling them up.
Heat a griddle or nonstick skillet over medium heat and grill each burrito for about 30-60 seconds per side until golden brown.