Line a baking sheet with parchment paper; set aside.

Preheat oven to 325°F.

Using an electric mixer, beat egg whites until stiff peaks form.

Using a medium bowl, add almond flour, powdered sugar, baking powder and salt; stir until well combined.

Fold whipped egg whites into the bowl with dry ingredients, taking care not to over-stir.

Add lemon juice, orange zest, almond extract and vanilla extract; fold just until combined.

Working with ~ 1 Tbsp of dough, roll it into a round ball. (Tip: Dip your fingers in powdered sugar to keep dough from sticking to your hands too much.) Shape dough into an oval or log and then roll in extra powdered sugar. Place cookie on parchment-lined sheet pan.

Once all cookies have been placed on sheet pan, flatten the tops slightly with the palm of your hand.

Top each cookie with 1-2 sliced almonds.

Bake for 20-22 minutes, or until cookies are light golden brown.

Let cool for 10 minutes before transferring to a cooling rack until completely cooled.

Dust lightly with powdered sugar before serving.