In a small bowl, whisk together the mayonnaise, sour cream, jalapeño juice, garlic powder, onion powder, paprika, cumin, and salt. Taste and adjust seasoning as desired. Cover and refrigerate while preparing the chicken and quesadillas.

Heat the oil or butter in a skillet over medium heat. Add the diced chicken, salt, black pepper, garlic powder, paprika, and cumin. Stir until the chicken is browned, cooked through, and evenly coated with the seasonings. Remove from heat.

Spread a thin layer of creamy jalapeño sauce over half of each tortilla. Add a portion of the seasoned chicken, a handful of shredded Mexican blend cheese, and a sprinkle of Pepper Jack. Fold each tortilla in half to close.

Heat the butter in a large skillet over medium heat. Place one or two quesadillas in the pan and cook for 2 to 3 minutes per side, or until golden brown and crispy with melted cheese inside.

Slice into wedges and serve hot with extra creamy jalapeño sauce for dipping.