Beat egg yolks in a medium mixing bowl with an electric mixer on high speed about 6 minutes or until yolks are thick and lemon-color. Add the 1/3 cup sherry. Beat on low speed until combined. Gradually add the 2/3 cup sugar, beating on medium speed about 5 minutes or until sugar is almost dissolved and mixture has almost doubled in volume. Fold flour into egg yolk mixture about half at a time. Fold in ground almonds.
Thoroughly wash beaters. Beat egg whites and cream of tartar in a large mixing bowl on medium to high speed until soft peaks form (tips curl). Gradually add the 1/3 cup sugar, about 1 tablespoon at a time, beating on medium to high speed until stiff peaks form (tips stand straight).
Fold about 1 cup of the egg white mixture into the egg yolk mixture. Then fold all of the egg yolk mixture into the remaining egg white mixture. Pour batter into two ungreased 8x1-1/2-inch round baking pans. Bake in a 325 degree F oven about 25 minutes or until the cake tops spring back when lightly touched in the center.
Invert onto racks ( leave in pans); cool. Remove from pans.
To assemble, place first cake layer on a large serving plate. Spread top with raspberry or strawberry preserves. Top with remaining cake layer.
Combine whipping cream, the 1 tablespoon sugar, and the 1 tablespoon sherry in the chilled bowl. Beat on low speed until soft peaks form. Spread on top and sides of cake. Cover and chill 1 to 2 hours. Just before serving top with berries and, if desired, garnish with a lavender sprig. Makes 12 servings.