Cake: Preheat oven to 375 F. Line three 9" layer cake pans with buttered parchment. Melt the chocolate in a double boiler; cool. Cream the shortening; gradually add the sugar and cream until fluffy. Add the egg yolks and vanilla; beat well. Reserve two tablespoons of flour. Sift the remainder of the flour with the baking powder and salt; add alternately with the milk to the creamed mixture. Beat the batter about one minute. Dredge the nuts in the reserved flour, then fold them into the mixture. Bake for 45 minutes, then cool the layers in the pans for ten minutes; turn out onto a wire rack to finish cooling. Frost.

Frosting: Melt the chocolate in a double boiler; add the butter and one cup of confectioners' sugar, and beat well. Add the egg, vanilla, lemon juice and enough confectioners' sugar to give a proper spreading consistency. Add the nuts; spread the frosting on the cake.