In a large bowl, combine grated zucchini, eggs, chopped dill, feta cheese, and cheddar cheese. Slowly stir in the flour, mixing well. Add salt and cayenne pepper and mix thoroughly.
Grease a 9-inch baking pan with butter. Pour the zucchini mixture into the pan and dot the top with remaining butter.
Bake for 45 minutes or until the casserole is golden brown and set. Serve warm or cold.
Notes
This dish can be prepared ahead and reheated. Great served with a fresh green salad.