Position racks in the upper and lower thirds of the oven and preheat to 325 degrees . Line 2 cookie sheets with parchment paper. Using a food processor, grind the almonds with 1 tablespoon granulated sugar. Transfer to a large bowl; whisk in the flour, cornmeal and salt.
Using a food processor, combine the butter, lemon peel and remaining 3/4 cup granulated sugar until creamy. Scrape down the bowl, add the egg and process until combined. Stir into the flour mixture. Quarter the dough, cover with plastic wrap and refrigerate for 20 minutes.
On a lightly floured surface, using a floured rolling pin, roll out one-quarter of the dough into a 9-inch round. Using a 2 1/2-inch heart-shaped cookie cutter, cut out cookies and, using a metal spatula, transfer to a prepared cookie sheet. Repeat with the remaining dough. Bake until lightly colored, about 15 minutes; transfer to a rack to cool.
Spread the flat side of half of the cookies with about 1 teaspoon jam; sandwich with the remaining cookies. Dust lightly with the confectioners' sugar.