Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the diced onion, red bell pepper, and green bell pepper. Sauté for 5-7 minutes, until vegetables begin to soften.

Add the sliced mushrooms to the skillet and continue to cook for another 5-8 minutes, stirring occasionally, until mushrooms have released their moisture and started to brown.

Stir in the rinsed and drained black beans, corn, chili powder, cumin, smoked paprika (if using), garlic powder, salt, and black pepper. Cook for 3-5 minutes, stirring to combine and heat through the beans and corn, allowing the flavors to meld. Remove from heat and set aside.

Wipe out the skillet if necessary, or use a clean one. Heat 1/2 tablespoon of olive oil (or butter) in the skillet over medium heat.

Place one flour tortilla in the hot skillet. Sprinkle about 1/4 cup of shredded cheese over half of the tortilla. Spoon approximately 1/4 of the vegetable filling over the cheese.

Sprinkle another 1/4 cup of shredded cheese over the vegetable filling. Fold the other half of the tortilla over the filling to create a half-moon shape.

Cook for 3-5 minutes per side, or until the tortilla is golden brown and crispy, and the cheese is thoroughly melted and gooey. Press down gently with a spatula to ensure even cooking.

Remove the cooked quesadilla from the skillet and transfer to a cutting board. Repeat the process with the remaining tortillas, filling, and cheese, adding more olive oil/butter to the skillet as needed.

Slice each quesadilla into 2 or 3 wedges. Serve immediately with your favorite toppings such as salsa, guacamole, sour cream, or fresh cilantro.