Prep your pan. Preheat the oven to 350 degrees F. Line an 8x8 inch square pan with parchment paper and spray with nonstick cooking spray. Set aside.
Prep the zucchini. First, measure out 1 cup of shredded zucchini, then place shredded zucchini in a paper towel or cheese cloth and squeeze out all of the moisture/water. This is very important!
Mix the wet ingredients. Add shredded zucchini, eggs, honey, lemon zest, lemon juice and almond extract to a large bowl and whisk together until well combined.
Add dry ingredients. Almond flour, oat flour, baking soda and salt. Mix together with a wooden spoon until well combined.
Add the blueberries. In a separate medium bowl, toss blueberries together with 2 tablespoons of oat flour. (This is to prevent the blueberries from sinking to the bottom of the cake while baking.) Fold coated blueberries into the batter.
Bake the cake. Pour batter into the prepared pan. Bake for 30-35 minutes or until a tester comes out clean. Allow the cake to cool completely on a wire rack before frosting. I know this is difficult but it’s critical (otherwise the frosting will melt and become a gooey mess!)
Make the frosting. Beat together butter, powdered sugar, lemon juice and lemon zest together on high with a hand mixer or in the bowl of an electric mixer until smooth. Spread frosting over cooled cake. Garnish with a few blueberries. Cut into 9 slices and enjoy!
