Preheat oven to 250°F (121°C). Line two large baking sheets with parchment paper or silicone baking mats. Set aside.

Melt the chocolate first so it can cool down before folding into the batter. You can melt the chocolate in a double boiler or the microwave. If using the microwave: place the chopped chocolate in a medium heat-proof bowl. Melt in 20 second increments, stirring after each increment until completely melted and smooth. Set aside.

In a completely clean residue-free large glass or metal mixing bowl, using a handheld mixer or stand mixer fitted with a whisk attachment, beat the egg whites, cream of tartar, and salt together on high speed until soft peaks form, about 2 minutes. With the mixer running on high speed, slowly add the sugar and beat until stiff glossy peaks form, about 2 more minutes. Do not over-beat.

Gently fold in the chocolate. To maintain swirls, you don’t want to completely mix it in. Don’t worry if you don’t use all 2 ounces—you can add some to the piping bag in the next step.

Add an open star piping tip (I recommend Wilton 1M) to your piping bag (disposable or reusable). Drizzle any leftover chocolate along the inside of your piping bag (this is optional). Add the meringue batter. It won’t all fit, so only use half to start.

Pipe 1.5 inch swirls until you use up all the batter. See the video tutorial above if you need a visual. The cookies don’t spread, so you can pipe them just 1-2 inches apart. Top each with sprinkles, if desired.

Bake for 1 and 1/2 hours. (You can bake both baking sheets at once.) Do not open the oven as the meringues bake. Turn off the oven after 1.5 hours and let the meringues sit inside as the oven cools for 30 minutes or until the oven has cooled completely.

Remove meringues from the oven and cool completely on the baking sheets. Once cool, use a flat spatula to remove the meringues from the baking sheets.

Cover and store meringues at room temperature for up to 2 weeks.