Terrie in MD hit the nail on the head. So many people think they must use all butter when baking. With chocolate chip cookies, they may be good but they will be flat. Use half shortening as Terrie suggests.

After years of doing this with the recipe on the back of Nestle's chip package (I'm old enough that I remember when it was all shortening listed on the bag!), I changed recipes this year. You might want to try it. It was posted by LoriD./Fl some time ago. In the search box, type in Beth's Chocolate Chip Cookies and you will see the post. It is excellent - if you like soft and chewy cookies. Key is not to overbake them (you may think they are not done but they will be). It uses all light brown sugar so they will be a lighter color than when using dark brown. Once I tried half light brown and half dark brown and they weren't as soft and chewy. Good luck!