Butter and flour a 9 inch cake pan. Preheat oven to 325 degrees. Put eggs, sugar, salt and rum in a large bowl and beat with the electric mixer until the mixture is white and thick and spins a very heavy ribbon when falling from the beaters; fold in the flour, then fold in the melted butter. It is essential never to stir so as not to deflate the batter. Turn into a prepared cake pan and bake 40 minutes on the lowest rack of a 325 degree oven. Invert onto a cake rack, let cool completely and split into 2 layers. To make the butter cream, put egg yolks, sugar, and coffee dissolved in rum in a large mixing bowl. Beat until very thick, light in color and spinning a heavy ribbon. Cream in the butter, tablespoon by tablespoon, until it has been completely absorbed. Toast the sliced blanched almonds in a 350 degree oven for 6 to 8 minutes or until golden. Cool. Fill the cake with 2/3 of the cream. Spread the remainder all around its sides and top; spread the almonds all over the cake and dust lightly with confectioners' sugar. 12 to 16 servings.