Makes: 18 sandwiches
1 cup almond meal/flour or finely ground almonds
1 2/3 cups powdered sugar, plus more for sprinkling
1 1/2 teaspoons red-fruit Jell-o powder (such as raspberry, strawberry, or cherry)
3 large egg whites, at room temperature
1/4 cup granulated sugar
1/2 cup vanilla frosting
Sift together almond meal, powdered sugar, and Jell-o into a large bowl. Discard any large chunks. Set aside.
In a large bowl, with an electric mixer on medium speed,whisk egg whites until frothy and light, about 1 minute. With mixer running, gradually add granulated sugar. Increase speed to high and whisk until stiff peaks form, about 2 more minutes.
Using a rubber spatula, gently fold almond mixture into whipped egg whites just until batter no longer holds whipped peaks. Batter should be thick but still fow slowly. Do not overmix or batter will become runny.
Line a cookie sheet with parchment paper. Fit a pastry bag with a 1/4 inch round tip and fill with batter. Pipe 36 rounds 1 1/2 inches in diameter onto prepared cookie sheet. Let the piped cookies stand uncovered at room temperature for 1 hour.
Meanwhile, preheat oven to 300F.
Bake for about 15 minutes, or until set. Do not let brown. Cool completely on pans. Use an offset spatula to lift cookies of parchment, if necessary.
Spread about 1 teaspoon frosting onto the flat side of half the cookies and press the remaining cookies on top, bottom side in, to form sandwich cookies. Sprinkle with powdered sugar.