Preheat oven to 350F. Line an 8x8 square baking pan with parchment paper and set aside.

Make the crumble by whisking the dry ingredients together in a medium bowl then cutting in the coconut oil until you have a sand like texture that holds together when pinched. Set aside.

Mix together the cinnamon-sugar mixture in a small bowl and set aside.

Whisk together the dry ingredients for the cake in a medium bowl.

Use an electric mixer or stand mixer to beat together the wet ingredients for the cake in a large bowl.

Add the dry mixture to the wet and mix on low until just combined. Or use a rubber spatula to fold in the wet ingredients.

Scoop half the batter into the prepared pan and spread evenly. Sprinkle the cinnamon sugar mixture over the top then gently spread the remaining cake batter on top. Crumble the streusel topping evenly over the top of the entire cake, making sure to get all the way to the edges.

Bake for 25-30 minutes, until a toothpick inserted in the center of the cake comes out with a few crumbs and the top is golden brown.