Grind the almonds: In a food processor, pulse the blanched almonds until very finely ground, like a coarse flour. Be careful not to process too long or it will turn into almond butter.

Combine dry ingredients: In a large bowl, mix the ground almonds and confectioners' sugar.

Add wet ingredients: Gradually add egg whites, one at a time, mixing until a stiff, pliable dough forms. If using, add almond extract. The dough should be firm enough to shape but not crumbly. You might not need all the egg whites.

Chill the dough: Wrap the dough in plastic wrap and chill in the refrigerator for at least 1 hour, or overnight.

Prepare pans: Grease and flour (with rice flour for gluten-free) kransekake ring molds, or prepare baking sheets lined with parchment paper if shaping by hand.

Shape the rings: Divide the dough into 18 equal portions. Roll each portion into a long, thin rope (about 1/2 inch thick). Form each rope into a ring, sealing the ends together. Gradually increase the size of the rings to create a tiered cake.

Bake: Preheat oven to 375°F (190°C). Bake the rings for 12-15 minutes, or until lightly golden brown. They should be firm on the outside but still slightly soft in the center. Let cool completely on a wire rack.

Prepare icing: Whisk confectioners' sugar with egg whites (or lemon juice) until a thick, smooth icing forms.

Assemble: Once cooled, stack the rings from largest to smallest, using the icing to "glue" them together. Drizzle extra icing over the stack in a decorative pattern.

Decorate (optional): Garnish with small flags, candies, or marzipan decorations.