Black Bean and Corn Quesadillas

Quesadillas are a staple in my family's menus.  We make them with plain cheese, cheese and chorizo, cheese and chicken, cheese and carnitas....the list goes on and on.  I am planning to try these while the fresh sweet corn is still plentiful.

2 teaspoons olive oil 3 tablespoons finely chopped onion 1 (15.5 ounce) can black beans, drained and rinsed 1 (10 ounce) can whole kernel corn, drained 1 tablespoon brown sugar 1/4 cup salsa 1/4 teaspoon red pepper flakes 2 tablespoons butter, divided 8 (8 inch) flour tortillas 1 1/2 cups shredded Monterey Jack cheese, divided 1. Heat oil in a large saucepan over medium heat. Stir in onion, and cook until softened, about 2 minutes. Stir in beans and corn, then add sugar, salsa, and pepper flakes; mix well. Cook until heated through, about 3 minutes. 2. Melt 2 teaspoons of the butter in a large skillet over medium heat. Place a tortilla in the skillet, sprinkle evenly with cheese, then top with some of the bean mixture. Place another tortilla on top, cook until golden, then flip and cook on the other side. Melt more butter as needed, and repeat with remaining tortillas and filling.