Preheat the oven to 325°F (160°C). Line a baking sheet with parchment paper.
Grind the almonds finely using a food processor until powdery.
Mix the almonds and powdered sugar in a bowl.
Whisk the egg whites lightly in a separate bowl. Slowly fold them into the almond-sugar mixture to form a pliable dough.
Shape the dough into ropes and then form rings of decreasing size (8–12 rings is traditional). Place them on the prepared baking sheet.
Bake the rings for 10–12 minutes. They should be lightly golden and slightly soft to touch.
Cool the rings completely before stacking.
Assemble the cake by stacking the largest ring on the bottom and gradually placing smaller rings on top. Use royal icing to stick layers together if needed.
Decorate with drizzled icing, chocolate, or festive touches as desired.