Put Almonds and flour in the work bowl of a food processor, fitted with the metal blade, and process until finely ground. set aside.

Beat butter in med. bowl until lightened in color and texture, 2-3minutes. Add sugar, continue beating until mixture is very light, about 5 min. longer. Grate 1 tbsp lemon zest and beat in along with vanilla Stir in flour mixture, being careful NOT to over mix. Form the dough into a 1/2" thick disk. Wrap in plastic and refrigerate until firm (about 1 hour) May be refrigerated overnight

Line 2 baking sheets with parchment. Cut dough into 4 even pieces; set aside 3 pieces. Carefully roll out the dough 1/8" thick on a floured surface. Cut out 1.5" circles with plain or fluted cookie cutter. Press scraps of dough into a ball; roll and cut out more circles. To form the cookie tops, cut out the centers of half of the dough circles with a 1/2" canape cutter, or the
bottom of a metal pastry tip. Put cookie rings and bottoms 1/2" apart on baking sheet. Repeat to cut out circles and rings from the remaining pieces of dough.

COOKING: Adjust oven racks to low and middle positions; heat oven to 325F Whisk the egg white with the salt. Coarsely chop the almonds or crush with rolling pin. Brush the cookie tops with egg wash and sprinkle with crushed almonds. Bake until cookies are dry and very lightly browned (12-15 min.) If baking two sheets at the same time, switch them after 6 min to ensure even cooking. Cool cookies on the baking sheet

Bring 1/2 cup jam to a boil in a small saucepan, and simmer until
slightly thickened (5-8 min) Brush the cookie bottoms with the jam, and top with the cookie rings. Dust with confectioners' sugar. Use a small spoon or pastry bag fitted with a 1/4" tip to fill the holes with the remaining jam.