Preheat the oven to 350ºF, and lightly grease a 9″x13″ glass baking dish. Make sure to take the butter out of the refrigerator for the frosting so it has time to soften.

In a medium sized mixing bowl, combine the almond flour, tapioca starch, sea salt, baking powder, and baking soda stirring until no lumps remain. Add the maple syrup, eggs, butter, vanilla, lemon juice, and almond extract. Stir just to combine, then pour the cake batter into the prepared pan. Use a spatula if necessary to even out the top of the cake.

Bake for 20-24 minutes, or until the cake is puffed in the middle and a toothpick inserted into the center comes out clean or with moist crumbs. Cool the cake to room temperature on a cooling rack.

To make the frosting, add the softened butter to a mixer with the whip attachment. Beat the butter until it’s smooth. Then add the powdered sugar, vanilla extract, lemon juice, and almond extract. Beat on low speeds until the powdered sugar is combined. Add 2  Tablespoons of the heavy cream and beat again starting on low and working up to high. Beat the frosting until it’s fluffy, 1-2 minutes, adding the extra tablespoon of heavy cream if the frosting seems too stiff.

Spread the buttercream over the cooled cake, then top with the berries using the blueberries to create the ‘stars’ and the sliced strawberries to create the ‘stripes’. 

Serve the cake with the extra berries.