Preheat oven to 350 F. Line a square 8×8-inch baking dish with parchment paper.
In a small bowl, combine the nondairy milk and vinegar and stir. Set aside.
In a large mixing bowl, add the flour, oat flour baking powder, cinnamon and sugar, Whisk to combine.
Add the nondairy milk mixture, apple sauce and oil and stir to combine.
Pour into prepared baking dish.
In a small mixing bowl, combine topping ingredients and mix with a pastry blender or your hands until its crumbly. Gently pour evenly over the cake.
Bake 33-35 minutes, until a toothpick inserted in the center comes out clean or with a few crumbs clinging.
Let cool slightly, as it tastes sweeter when it has sat for at least 10-15 minutes and isn’t piping hot. Serve warm with berries and a drizzle of maple syrup. Store in an airtight container at room temperature for up to 4 days, or freeze for up to 3 months.
