Preheat your oven to 350 °F and grease an 8 inch cake pan (preferably springform) with cooking spray.
In a small bowl prepare your flax egg by whisking together 1 tablespoon of ground flaxseed with 3 tablespoons of water. Set aside to thicken.
In a mixing bowl, whisk together the flour, baking powder, salt and cinnamon.
In a separate bowl, cream together the softened coconut oil and coconut sugar until combined. Add in the thickened flax egg and vanilla and cream again until a wet mixture forms.
Alternately add in the flour mixture and the 1 cup of non-dairy milk to the oil/sugar mixture, being careful not to over mix.
Once combined fold in the blueberries.
Pour the batter into your prepared cake pan and set aside.
In a bowl prepare the streusel topping by combining the 3 tablespoons of coconut oil, flour, coconut sugar, salt and cinnamon in a bowl and using a fork to cut the coconut oil into the dry ingredients until a crumby mixture forms.
Evenly sprinkle the streusel mixture over the batter.
Bake the cake for 30 minutes. Remove from the oven, cover with aluminum foil and bake for about 10 more minutes or until toothpick inserted into the center comes out clean.
Allow the cake to cool for a bit before serving.