Most cake mixes are safe to use for three months after the expiry date if the package is kept unopened. However, it is wise to contact the manufacturer and check whether the product is fit for consumption. The pack will have company details and a phone number to call during office hours or a website. The main problem with using the cake mix after the expiry date is that the baking soda might have lost its potency. This may not be an issue if you make cookies with the cake mix.
Baking Cake Mix Cookies
Preheat the oven to 350 degrees Fahrenheit.
Combine the cake mix, softened butter and the egg in a bowl. Mix together thoroughly until it forms a smooth dough.
Use a tablespoon to drop the dough on to the cookie sheets. Allow a little space around the dough for the cookies to expand in the oven.
Bake the cookies for 10 to 12 minutes in the preheated oven. Remove from the oven and allow to cool for two minutes before moving them to a wire rack to cool completely.
Store the cake mix cookies in an airtight container. Leaving them at room temperature will help them to retain their softness.