Preheat oven to 375 degrees.
Heat the olive oil in a large cast iron skillet over medium-high heat. Add the peppers and onion. Sprinkle with desired amount of salt & pepper. Saute until the peppers & onions are soft and starting to brown. Remove from the heat and add the black beans and toss to combine.
In a medium bowl combine the cheddar and Monterey Jack cheese together until combined.
Brush the one sire of the flour tortillas and flip so the non-greased side is facing up. Layer a 1/2 cup of the cheese mixture on one half of each tortilla. Layer the black bean veggie mix over the bottom layer of cheese. Layer another 1/2 cup of the cheese mixture over black bean and veggie layer.
Fold the other half of the tortillas to make a half moon. Place the tortillas on a large baking sheet. (You may need tow baking sheets.)
Bake in the oven for 6 to 8 minutes. Carefully flip the quesadillas and bake for another 6 to 8 minutes or until the tortillas start to brown.
Slice the tortillas into triangles and enjoy with salsa, sour cream, guacamole, etc.