The combo of zucchini and onions in a kugel is not a novel idea, but little twists on an old pairing makes for a fresh dish. Here the proportion of onion to zucchini is higher, so the onion flavor is more prominent. Then the addition of apple adds just the right touch of sweetness, apparent only to the most discerning palates. Grating the veggies on different discs adds interesting textural element. Can be frozen.