Add the pumpkin and black beans to large bowl. Stir well. Next, stir in the cilantro, chili powder, cumin, salt, paprika, and cayenne, if using. Divide the filling into 4 portions.

Lay 4 tortillas on a flat surface. Top each with a portion of the filling and spread to cover the tortilla. Top each with ¼ of the shredded cheese. Place the remaining tortillas over the filling to make 4 quesadillas.

For each quesadilla, melt a ½ tablespoon of butter in a large skillet over medium-high heat. Add the quesadilla and cook for 3 to 4 minutes on each side, until the tortilla is golden brown and the filling is warm.