In a small glass mixing bowl, add the brown sugar, cinnamon and ⅔ cup gluten-free flour. Using a fork or a pastry cutter, cut in the vegan butter until a crumble forms. Gently sprinkle the crumble in the bottom of the bundt pan.
Add the vanilla, flax eggs, vegan sour cream and cream cheese and beat until combined.
Add in the gluten-free flour, baking powder and salt and stir until well combined, scraping down the sides of the bowl as needed.