Preheat the oven to 350 degrees Fahrenheight and line an 8" brownie pan with parchment paper both ways (or spray with cooking spray), set aside.

In a medium-sized bowl, whisk together the brown rice flour, oat flour, xanthan gum and salt, set aside.

*Rinse the blueberries and puree them in a blender. Measure 1+1/2 cups and pour into a large mixing bowl. Whisk in the erythritol, oil, lemon zest, stevia and food coloring.

Dump the dry ingredients over the wet and fold the batter until thoroughly mixed.  Scoop into the prepared brownie pan and spread to the edges using an offset spatula, making sure the surface is flat.

Bake for ~55 minutes, or until the edges pull away from the sides and the surface is firm.  Let blondies cool in the pan for 20 minutes, then transfer to a wire cooling rack to cool completely.

Measure 1/4 cup of the blueberry puree and stir in the food coloring. Stir in the erythritol.

Stir in the blueberry powder 1-2 tsp at a time (frosting should be very thick). Spread onto the cooled blondies, refrigerate for 10 minutes to firm up the frosting, slice and serve.