- 1/2 stick unsalted butter, melted, plus 5 tablespoons, room temperature, plus more for pan
- 1 1/2 cups almond flour (spooned and leveled)
- 1/4 cup plus 2 tablespoons potato starch (spooned and leveled)
- 1 1/4 teaspoons gluten-free baking powder
- 1/4 teaspoon fine salt
- 3 large eggs, room temperature
- 1/2 cup packed light-brown sugar
- 4 teaspoons pure vanilla extract
- 1 cup finely grated zucchini (from 1 medium zucchini), squeezed of excess liquid
- 8 ounces cream cheese, room temperature
- 1/3 cup confectioners' sugar
- 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.
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.