I got this out of a cookbook years ago and they never last long. They are so good.. I didn't have a cake box right on hand so estimated the size. This is great for company. Hope you enjoy as much as we do. Also if you don't want to use the chocolate mint you can use devil's food cake mix. The base is the cake mix and butter and egg The filling is the unflavored gelatin, boiling water, powdered sugar, butter, shortening and peppermint extract and green food coloring. The frosting is the chocolate chips and 3 tbsp butter.. Just wanted to make sure everyone understood. :) also you can use margarine instead of butter. I love butter though.