Preheat oven to 350 degrees and line a 9x9 dish with parchment paper
In a bowl combine butter, applesauce, milk, and egg until combined
Add the cake dry ingredients into the wet ingredients and fold until evenly combined. Be sure not to over mix
Add half the batter into the pan.
In a small bowl combine the filling ingredients and stir till evenly combined. Sprinkle over the batter
Dollop the remaining cake batter over the filling and gently spread to form another even layer of cake batter
In the same bowl you used for the filling add in ingredients for the topping. Stir to combine and crumble over the top of the cake batter
Bake for about 45 minutes until a knife comes out clean and cake is set
Let cool to allow the crumble to cool and then slice and serve.
Store in a airtight container for 3-5 days.