Now it’s time to mix up the cake. Follow the directions on the cake mix, except that you will substitute the pineapple juice for the water. If there isn’t enough, use water to make up the difference. Once the cake batter is ready, pour the batter into the cake pan and spread the cake batter out so that all of the brown sugar/pineapple mixture is covered. Bake 35-40 minutes or until a toothpick comes out clean.