Prepare Jiffy Mix as directed on the box, set aside to cool. Place zucchini and yellow squash in a large saucepan and add just enough of water to cover. Cook on medium low heat just until tender, remove from heat. Drain squash, reserve one cup of water for casserole. On medium low temperature place all of the butter in large sauce pan and sauté the onions until the onions turn clear, add salt, pepper, thyme, and parsley. Add chicken bouillon cubes and garlic to onions, stir. Add drained squash and diced cheese, stir. Crumble corn bread in squash and pour the reserved cup of water and mix well. Place squash mixture in a 13x11" baking pan that has been sprayed with a non-stick spray. *This is the point I freeze mine - can also be frozen in 2 small pans if desired. Then all you have to do is thaw when ready and cook! Cover casserole and place in a preheated oven at 350degreesF. Bake for 50-60 minutes. Remove cover the last 20 minutes of baking time. Lower Fat content by reducing amount of butter used by half.