Pulse confectioners’ sugar and almond flour in a food processor until combined. Sift mixture twice and set aside.
Preheat oven to 375 degrees Fahrenheit (190 degrees Celsius).
Whisk whites with a mixer at medium speed until foamy. Add potato starch and whisk until soft peaks form. Reduce speed to low, then add superfine sugar. Increase speed to high, and whisk until stiff peaks form, about 8 minutes. Sift flour mixture over whites and fold until mixture is smooth and shiny.
Transfer batter to a pastry bag fitted with a 1/2 -inch (1.25-centimeters) plain round tip, and pipe 3/4-inch (2-centimeters) rounds 1 inch (2.5 centimeters) apart on Gefen Parchment Paper lined baking sheets, dragging pastry tip to the side of the rounds rather than forming peaks.
Tap bottom of each sheet on work surface to release trapped air. Let stand at room temperature for 15 minutes.
Reduce oven temperature to 325 degrees Fahrenheit (160 degrees Celsius). Bake one sheet at a time, rotating halfway through, until macaroons are crisp and firm, about 10 minutes.
After each batch, increase oven temperature to 375 degrees Fahrenheit (190 degrees Celsius), heat for five minutes, then reduce to 325 degrees Fahrenheit (160 degrees Celsius).
Let macaroons cool on sheets for two to three minutes, then transfer to a wire rack.
If macaroons stick, spray water underneath parchment on hot baking sheet. The steam will help release macaroons.
Sandwich two same-size macarons together with one teaspoon filling. (Suggested fillings are listed above.) Serve immediately, or stack between layers of parchment, wrap in plastic, and freeze for up to three months.