Set your oven to 375°F (190°C).
In a large bowl, combine the shredded chicken, black beans, Rotel, garlic powder, onion powder, chili powder, cumin, salt, and pepper.
Brush a large baking sheet generously with melted butter. Arrange the tortillas around the edges of the pan so that half of each tortilla hangs over the sides. Place one tortilla in the center to cover any gaps.
Sprinkle half of the cheese evenly over the tortillas. Spread the chicken mixture on top, then layer with the remaining cheese.
Place one tortilla in the middle over the filling and brush it lightly with melted butter.
Fold the overhanging tortillas inward over the filling, overlapping them to completely cover.
Brush the folded tortillas with more melted butter to help them brown.
Place another sheet pan directly on top of the quesadillas to press them down and keep the tortillas flat while baking.
Bake for 35-55 minutes, or until golden brown and the cheese is fully melted. Cooking time will vary.
(Optional) While baking, whisk together sour cream, chipotle peppers, lime juice, and salt in a medium bowl until smooth. Adjust spice level to taste.
Remove the quesadillas from the oven, slice into squares or wedges, and serve warm with chipotle crema. Garnish with fresh cilantro or jalapeños if desired.