Preheat the oven to 350 F° and prepare a 6-inch (3-inch deep) round cake pan with non-stick spray.
In a mixing bowl, stir together the flour, tapioca starch, sugar, baking powder, baking soda, salt and zest. Add in the the almond milk, lemon juice, applesauce, coconut oil and vanilla extract and stir using a rubber spatula just until no spots remain.
Place all the crumble ingredients into a food processor and pulse until everything is well combined and crumbles form.
Transfer the batter to the pan and top with crumbles. Bake the cake for 35-40 minutes and cooked through and topping is golden. Remove from the oven and let cool. Stir together the glaze ingredients and drizzle over the cake.
Notes
This cake will keep at room temperature in a lightly covered container for up to 2 days or in the refrigerator for up to 5 days.