Melt the German's sweet chocolate in boiling water.

Allow the chocolate mixture to cool.

Cream the butter and sugar together until the mixture is light and fluffy.

Add the egg yolks, one at a time, beating well after each addition to fully incorporate.

Add the melted chocolate and vanilla extract to the creamed mixture.

Mix until well combined.

In a separate bowl, sift together the cake flour, salt, and baking soda.

Gradually add the dry ingredients to the chocolate mixture, alternating with the buttermilk, and beat after each addition until smooth.

Gently fold in the stiffly beaten egg whites until just combined. Be careful not to overmix.

Pour the batter into three 8 or 9-inch layer pans, lined on the bottom with parchment paper.

Bake in a preheated oven at 350°F (175°C) for 30 to 40 minutes, or until a wooden skewer inserted into the center comes out clean.

Allow the cakes to cool completely in the pans before frosting.

Frost the tops of the cake layers only with your favorite frosting.