Preheat oven to 350 degrees F and line 2 large baking sheets with parchment paper or silicone mats.
In a large mixing bowl, add black beans, corn, pepper, cilantro, red onion, cumin and salt; stir well to combine.
Build each quesadilla: on a half of tortilla sprinkle 3 tbsp (half of 1/3 cup) of cheese, spread 1/2 cup veggie mixture and sprinkle with remaining 3 tbsp of cheese. Fold the other half of tortilla on top pressing on it somewhat gently-hard making a half moon shape. Repeat and make 8 quesadillas. If you have any leftover veggie mixture, eat it.
Bake for 20 minutes. Remove from the oven, let rest for 3-5 minutes and cut each quesadilla in half using serrated knife.
Serve with salsa, sour cream or yogurt and any of your favorite toppings.
Notes
Store: While quesadillas taste best fresh, leftovers can be refrigerated up to 2 days.
Make ahead: Refrigerate filling mixture without salt covered for up to 2 days, then make quesadillas.
Freeze: Assemble, then wrap in plastic wrap as tightly as possible without compromising shape. Lay flat in a gallon size Ziploc bag, squeeze air out, seal and freeze up to 3 months. Bake from frozen at 350 degrees F for 25-30 minutes. Or cook in a panini press.
Reheat: Bake in air fryer at 400 F for 5 minutes, put on panini press or reheat on a skillet (no oil needed) until warmed through and crispy on the outside.