Preheat the oven to 350 degrees F and line an 8" x 8" cake pan with parchment paper.

Add the ingredients for the coffee cake, except for the blueberries, to a blender. Blend until combined and smooth. Note: the cake batter will be very thick - this is normal.

Toss the blueberries with 1 tsp coconut flour in a small bowl to ensure they won't all sink to the bottom of the coffee cake. Fold the blueberries into the coffee cake mixture.

Stir the ingredients for the walnut cinnamon swirl topping in a small bowl until well-combined.

Pour 1/2 to 2/3 of the cake batter into the prepared cake pan and smooth into an even layer. Evenly spread 1/2 to 2/3 of the walnut topping mixture on top of the cake batter and use a knife to swirl it into the batter.

Repeat for remaining cake batter and walnut topping.

Cover the coffee cake with foil and bake on the center rack of the preheated oven for 30 minutes. Remove the foil then bake for another 15 to 20 minutes, or until the cake has set up in the center and the edges are golden-brown.

Remove cake from the oven and allow it to cool at least 30 minutes (the longer the better) before cutting into it. Enjoy!