Preheat oven to 350 degrees F. Spray a 9” x 13” cake pan well with non-stick cooking spray.
In a large bowl, beat together cake mix, unsweetened applesauce, eggs, and vegetable oil. Beat until just combined and there are no more big lumps (about 2 minutes).
Pour cake batter into the prepared baking pan.
In a separate small bowl, stir together light brown sugar, ground cinnamon and melted butter until well mixed.
Use a spoon to place small scoops of this brown sugar mixture evenly around the top of the cake.
Use a table knife to swirl this brown sugar mixture into the cake batter until it looks well combined.
Place cake in oven and bake for 26 to 27 minutes or until toothpick inserted in middle comes out clean. Top of cake should look slightly brown. Remove from the oven and let cool completely.
Cinnamon Brown Sugar Frosting
In a large bowl, beat together (on high) confectioners’ sugar, butter, brown sugar, vanilla extract and ground cinnamon until light and fluffy (about 5 minutes).
Use a spatula to evenly coat top of cake with frosting. Let set for a few minutes before serving.
Notes
Make the brown sugar mixture immediately before swirling into the cake batter so that it easily combines.This cake is also delicious with cream cheese frosting or powdered sugar.