If spinach is frozen, thaw and press out extra moisture.
In a large bowl, mash the white beans with a fork or potato masher.
Stir in the spinach, cumin, coriander and salt. Stir/mash until the spinach is slightly wilted and fold in the feta cheese.
Heat a large pan over medium heat. Spray with oil, then assemble quesadillas in the pan (cooking 2 at a time).
Spoon out ½ cup of white bean/spinach filling, then sprinkle with ¼ cup cheese. Fold the tortilla over, then press down firmly.
Cook for 3 or so minutes per side, until golden and crispy.
