Any dessert will make you fat because of the processed sugar and fat in it. However, chocolate chips may make you fatter compared to a pineapple upside down cake or vanilla pound cake. That is because people crave chocolate after eating a little bit of it. Chocolate affects the brain in several ways. One way is to make people want more of it.
So, after eating a small piece of cherry pie or plum cake, you may feel full and do not want anymore. If you eat a chocolate chip cookie, you may want another one because of the chocolate that is in it. Then you may eat more cookies. Eating more cookies in one sitting will make the person ingest more sugar.