Quesadillas

500 gm frozen spinach, defrosted and squeezed thoroughly to remove water 375 gm grated cheese 425 gm tin of black beans, drained 410 gm tin whole kernel corn, drained ½ cup black olives, chopped 4 Tblspn salsa 1 cooked chicken breast, shredded (optional)

20 to 24 small or 10 to 12 large tortillas