1. Preheat oven to 350 degrees. Butter two 8-inch round cake pans and line with parchment paper. Butter parchment and flour cake pans; set aside.

2. In the bowl of an electric mixer fitted with the whisk attachment, beat together 1 cup of sugar and egg yolks until light and fluffy. Add orange zest, juice, and almond extract; mix until well combined. Turn mixer off. Remove the whisk and add the paddle attachment. With the mixer on medium, slowly add ground almonds, followed by flour; mix cake batter until well combined.

3. In a large bowl, whisk egg whites until soft peaks form. Add salt and remaining 3 tablespoons sugar; beat until stiff but not dry. Set aside.

4. Fold melted butter into cake batter, a little at a time. Gently fold in egg white mixture, taking care not to deflate whites. Divide batter evenly between prepared cake pans. Transfer to oven and bake until a cake tester inserted in the center of each cake comes out clean, about 35 minutes. Transfer cake layers to a wire rack to cool completely.

5. Invert cakes to remove from pan and remove parchment paper; reinvert cakes. Using a serrated knife, trim tops of cakes to make level. Place four strips of parchment paper around perimeter of a serving plate or lazy Susan. Place the first layer on the cake plate. Spread frosting over the first layer with a small offset spatula so it extends just beyond edges.

6. Place the remaining layer on top, bottom-side up. Gently sweep away any loose crumbs with a pastry brush. Using an offset spatula, cover the top and sides with a thin layer of frosting (also use any of the excess frosting visible between the layers). Refrigerate until set, about 30 minutes.

7. Using an offset spatula, cover cake again with remaining frosting.