This is how my mom always loved to fix summer squash. Simple and fast!
Cut squash into rounds. Put rounds and onions in saucepan and fill up halfway up the squash with water. Add a sprinkle of salt. Bring to a boil for 3-5 minutes. Add butter and cover. Lower the heat to simmer for 8-10 minutes. Turn off heat and add parsley or chives, taste for salt and pepper. Let flavors blend together for at least 10 minutes. Serve.