Preheat the oven to 325 F and line two 1/8th sheet baking pans (I used these) with lightly greased parchment paper.
Add the apple sauce, water, vanilla, and eggs to a large bowl and whisk well to combine. Add the cake mix and fold in the wet ingredients until a smooth batter forms.
Divide the batter between the two baking pans and transfer it to the oven. Bake for 10-12 minutes or until the brownies are firm and baked through. Set aside and allow to cool completely in the pans.
Once the cake are cool to the touch, use an ice cream scoop to add the ice cream to the top of one of the brownie pans. Use a silicone spatula to evenly spread the ice cream.
Repeat the process with the jam, covering the ice cream in an even layer.
Carefully flip the other cake pan onto the brownies with the ice cream and cover with plastic wrap or foil. Transfer to the freezer and allow to set for 6 hours, preferably overnight.
Once fully set, slice into 9 (or more) and serve!
Notes
The original recipe on the back of the cake mix calls for 1/3 cup of oil, but I swap 1/3 cup of applesauce to cut costs and find that it works well in this recipe! Of course, can easily use the oil instead.