Position racks in the upper and lower thirds of the oven; preheat to 250 degrees F. Line 2 baking sheets with parchment paper.
Beat the egg whites, cream of tartar and salt in a large clean dry bowl with a mixer on medium speed until foamy. Increase the speed to medium high and beat until thick and opaque, about 1 more minute. Gradually add the confectioners' sugar, about 1/4 cup at a time, and beat until stiff shiny peaks form, about 5 more minutes.
Transfer the meringue to a pastry bag fitted with a large round tip. Pipe about seventy 1-inch drops on the baking sheets, pulling the bag up to form a peak; leave space between each. Bake at 250 degrees F until dry and crisp, about 3 hours. Let cool completely on the baking sheets. Store in an airtight container in a dry place for up to 1 week.
Combine the white chocolate chips and coconut oil in a microwave-safe bowl; microwave, stirring every 30 seconds, until melted. Dip the bottoms of the meringues into the white chocolate, then dip in red sanding sugar; let set on parchment.
Meringues can be very sensitive to temperature, humidity and the final texture of the beaten egg whites. Cracking can happen with even minor differences to any of these factors but the baked meringues will still be crisp and tasty.
Photograph by Ryan Dausch
This recipe has been updated and may differ from what was originally published or broadcast.