Step 1

Preheat oven to 375°

Step 2

Butter a 8 or 9 inch loaf pan, then line it with a parchment paper sling. Butter the parchment paper sling. A sling is just an extra long piece of parchment paper that extends out over the two long edges of the loaf pan. This will give you "handles" to help you pull the cake out of the pan easily.

Step 3

Place room temperature butter, sugar, lemon zest, lemon juice, and vanilla in a bowl and mix well. If have stand mixer, use the paddle attachment.

Step 4

Beat on high speed for 3 to 4 minutes. Lower the speed to medium and add eggs one at a time, scraping down the sides of the bowl as you go.

Step 5

In another bowl, add all purpose or GF flour substitute, almond flour, baking powder and salt and whisk together. Add the dry ingredients, one third at a time, to the wet ingredients until just mixed.

Step 6

Fold in 3/4 of the blueberries by hand. Pour batter into the parchment-slinged loaf pan.

Step 7

Bake for 15 minutes at 375°. Remove from oven and sprinkle the last of the blueberries over the cake. Bake for another 15-20 minutes. The cake should be a light golden brown color. Cover loosely with foil and bake for an additional 25-30 minutes until it rises up and is fully cooked. Test for doneness by inserting a knife in the center of the cake. If it comes out clean, it is done.

Step 8

Cool for 10 minutes in the pan, then remove the cake onto a cooling rack and let cool completely.

Step 9

Make the icing once the cake has cooled. Whisk together confectioners' sugar and lemon juice. You might need to add a bit more lemon juice so that the icing is thinner than frosting, but not as loose as a glaze. It should be just barely pourable.Pour the icing over the cake and carefully spread it out. It's best if it sets for about 30 minutes before serving.