In a skillet, heat a bit of olive oil over medium heat. Add the diced onion and cook until translucent, about 2-3 minutes.
Add the chopped spinach to the skillet and cook until wilted, about 2-3 minutes.
Add the cooked black beans, corn kernels, ground cumin, chili powder, salt, and pepper to the skillet. Stir well to combine and cook for another 2-3 minutes until everything is heated through. Remove from heat.
Heat a separate skillet or griddle over medium heat. Place one tortilla on the skillet and sprinkle about ¼ cup of vegan cheese evenly over the tortilla.
Spoon a quarter of the spinach and bean mixture over half of the tortilla. Fold the other half over the filling to form a half-moon shape.
Cook the quesadilla for 2-3 minutes on each side, or until the tortilla is golden brown and the cheese is melted. Repeat with the remaining tortillas and filling.
Once all the quesadillas are cooked, remove them from the skillet and let them cool for a minute or two before slicing them into wedges.
Serve the vegan spinach quesadillas warm with your favorite dipping sauce, such as salsa, guacamole, or vegan sour cream.
