Oil bottom of 9 x 1-1/2 inch round cake pan and line with waxed paper. Finely grind almonds in food processor, blender or nut-chopper.
In large bowl, cream butter and 6 tablespoons sugar. Beat in yolks, one at a time. Stir in vanilla and almonds.
In medium bowl, beat egg whites and salt to soft peaks; gradually add remaining sugar, beating until soft, glossy peaks form. Lightly fold 1/4 beaten whites into batter. Sift 1/4 flour over batter; combine lightly. Alternately add remaining whites and flour in this manner.
Pour batter into pan. Bake at 350° for 30 minutes or until tester inserted into center comes out clean. Cool on rack 10 minutes; remove from pan.
When cool, slice horizontally into 2 layers. Place bottom layer, cut side up, on plate; spread with preserves. Top with remaining layer, cut side down. Place doily on top; sprinkle with confectioners' sugar; remove doily.