Preheat oven to 350. Spray an 8x8 pan with cooking spray.
Combine melted coconut oil with coconut flour, sweetener, baking powder, vanilla, eggs, and coconut milk. Stir until smooth. Stir in the blueberries. Spread in the prepared pan.
Pulse the crumb ingredients in a food processor until large wet crumbs form. Sprinkle on top of the cake.
Bake for 45 minutes until the cake is lightly browned around the edges and feels firm when pressed with your finger.
Nutrition: The nutrition facts are for one piece. There are 16 servings in this recipe. Each serving has 2.5 NET carbs.Substitutions: Exchange the blueberries for raspberries, strawberries, or blackberries. Storage: Keep the leftovers in the fridge for five days or at room temperature for two days. Keep it airtight until you are ready to serve. To Freeze: I prefer to wrap each piece of cake individually because it lasts longer and better. It will stay in the freezer for up to 2 months and can be thawed to room temperature on the counter or be placed in the fridge. Notes on Sweeteners: