Step 1

Preheat the oven to 375 degrees F (190 degrees C). Line the bottom and sides of a 15 1/2x10 1/2x1-inch jelly roll pan with waxed paper.

Step 2

Beat egg whites, vanilla extract, and salt using an electric mixer in a mixing bowl until soft peaks form. Beat in 1/2 cup white sugar gradually until combined.

Step 3

Beat egg yolks in a separate bowl using an electric mixer until thick and lemon-colored. Fold into egg white mixture. Fold in flour and chopped walnuts carefully until combined. Spread batter into the prepared jelly roll pan.

Step 4

Bake in the preheated oven until cake springs back when lightly touched and a toothpick inserted into the center comes out clean, about 12 minutes.

Step 5

Remove from the oven and let cool for 5 minutes. Loosen sides of cake; turn out onto a towel sprinkled with sifted confectioners' sugar. Peel off wax paper and let cool to lukewarm, 5 to 10 minutes.

Step 6

Roll cake and towel together starting at the narrow end. Let cool completely on a wire rack, 15 to 20 minutes.

Step 7

While cake cools, beat cold heavy cream and 1 tablespoon white sugar together in a mixing bowl using an electric mixer just until stiff peaks form.

Step 8

Unroll cake and spread with whipped cream, reserving some for topping. Re-roll cake and let chill in the refrigerator for at least 30 minutes. Top with dollops of whipped cream and walnut halves. Slice and serve.