Preheat oven to 350 degrees. Butter an 8-inch round, 2-inch deep cake pan. Line with parchment and butter paper. Whisk together almond flour, potato starch, baking powder, and salt.
Set a large heatproof bowl over (not in) a pot with 1 inch barely simmering water. Add eggs and whisk until foamy, about 1 minute. Whisk in brown sugar and continue to whisk until mixture is fluffy and sugar is dissolved, 3 minutes. Remove bowl from pot and, using a mixer, whisk on high until mixture is thick and pale, 7 to 10 minutes.
With a rubber spatula, gently fold in melted butter, flour mixture, 1 tablespoon vanilla, and zucchini. Pour into pan and bake until cake is golden brown and a toothpick inserted in center comes out with moist crumbs attached, 25 to 30 minutes. Let cake cool completely in pan on a wire rack. Invert onto a cake platter.
With mixer, beat together room-temperature butter, remaining 1 teaspoon vanilla, and cream cheese until fluffy, about 3 minutes. Add confectioners' sugar and beat until combined. Spread on top of cake.
Shopping Tip
Look for almond flour (also called almond meal) in the baking aisle. To keep it fresh, freeze in an airtight container for up to 1 year.
Unbelievably good! Made this as a cupcake and served it at the mayor's taste of town event and no one knew it was gluten free. We make them all the time and freeze the extras. Just take out a few minutes before serving to warm to room temp. Freezes very well.
sooo light and delicious. and a great cake for all your extra garden zucchinni!