Using a food processor, chop the nuts with 2 tbsp. confectioners sugar for 20 seconds. Scrape down and repeat until finely ground. Add the flour and pulse to mix.
Using an electric mixer, combine the butter, remaining 6 tbsp. confectioners sugar, the vanilla and salt; mix at low speed until just blended. Add the nut flour and mix just until incorporated.
Preheat the oven to 325 degrees . Line 2 cookie sheets with parchment.
Quarter the dough; shape into 4 disks. Roll out each disk 1/4 inch thick between 2 sheets of wax paper. (While you're working with 1 disk, cover the others with plastic wrap.)
Using a 2-inch round cutter, cut out cookies and transfer to the prepared pans. Using a 1-inch round cutter, cut holes in the centers of half of the cookies. Press the circle cutouts together with the rest of the dough scraps, reroll, then cut out more cookies. Refrigerate the cookies for 10 minutes.
Bake until the cookies are pale golden, about 8 minutes. Let cool on the pan for 2 minutes; transfer to racks. While the cookies are still warm, spread about 1/2 tsp. jam on each whole cookie, mounding in the center. When the cookies are cool, dust the cookie rings with confectioners sugar and place on top of the jam-topped cookies.