Preheat oven to 350F. Line an 8x8 inch baking dish with parchment paper.
Mix the flours together for the crumb topping.
Add the oil and maple syrup and mix together until you get a crumb texture that holds together when pinched. Set aside.
Whisk the flours, baking powder, baking soda, and salt together in a medium bowl and set aside.
Beat together oil and sugar with a paddle attachment until smooth.
Add in remaining wet ingredients and beat to combine.
Add in the dry ingredients to the wet and mix on low until just combined and you have a few flour streaks remaining.
Toss diced apples with the flour and cinnamon to coat. Fold apples into the batter.
Pour batter into prepared baking dish. Crumble topping evenly over the cake.
Bake for 35-40 minutes, until a toothpick comes out clean from the center and top is golden.
Let cool and enjoy!