Preheat the oven to 350°F. Line a baking sheet with parchment paper.

Beat the egg with the sugar in a mixing bowl. Sift in the flours and starch and mix thoroughly. Add the honey, coconut oil, lemon zest, and lemon juice. Mix until perfectly smooth. Place on a cutting board dusted with flour and knead for about 5 minutes. Roll the dough until it is about ¼-inch thick. Use a cookie cutter to cut out little hearts.

Place on the prepared baking sheet and bake for 15 minutes. Cool on a wire rack. Dust lightly with cocoa powder before serving.