Slice the zucchini and yellow squash in 1/4 inch thick round sliced. Chop the onion into long thin strips. Saute the squash and onion on butter (or olive oil) until slightly soft. Add the garlic and continue to saute. While the squash is cooking, dice the tomatoes. Add the tomatoes into the squash mixture and season with salt, pepper, parsley. Once tomatoes soften a little, sprinkle with parmesan cheese and serve warm. (Don't over cook the squash or it will be to soggy. Keep the squash a little tender to hold their form)