Step 1: Preheat your oven to 350°F (175°C).
Step 2: Grease your 9-inch round cake pan with butter or line it with parchment paper.
Step 3: In a large mixing bowl, whisk together the almond flour, potato starch, and baking powder.
Step 4: In another bowl, whisk the melted butter with sugar until smooth. Add eggs one at a time, then incorporate orange juice, zest, and almond extract.
Step 5: Gradually add the dry ingredients to the wet mixture, folding gently with a spatula.
Step 6: Transfer the batter into the prepared cake pan, smoothing the top.
Step 7: Bake for 30-35 minutes or until a toothpick comes out clean.
Step 8: Let the cake cool in the pan for 10 minutes, then invert onto a cooling rack.
Step 9: Dust the top with powdered sugar and garnish with sliced almonds.