Preheat the oven to 325 degrees F and line 2 baking sheets with parchment paper. Fit a pastry bag with a 1/2-inch round tip.
Combine the confectioners' sugar and pistachios in a food processor and grind until powdery. Sift through a fine-mesh sieve into a bowl and whisk in the cardamom.
Beat the egg whites and salt in a large bowl with a mixer on medium speed until frothy. Add the granulated sugar and beat until soft peaks form, 2 to 3 minutes. Add the food coloring and continue beating until stiff peaks form, about 1 to 2 more minutes. Fold in one-third of the nut mixture with a rubber spatula, then fold in the rest until just combined. Fold the batter a few more times until it slowly drips off the spatula (it will still be thick).
Transfer the batter to the pastry bag. Pipe about fifteen 1 1/2-inch circles onto each prepared baking sheet. Tap the baking sheets against the counter to release any air bubbles; let stand at room temperature until shiny and dry, about 15 minutes.
Bake 1 baking sheet at a time until the macaroons are slightly crisp and the bottoms release from the parchment, rotating the pan halfway through, 16 to 20 minutes. Let cool 5 minutes on the baking sheet, then transfer to a rack to cool completely.
Lightly dust the macaroons with edible glitter. Sandwich with preserves.
Photograph by Johnny Miller
Recipe courtesy Food Network Magazine