Preparation

Make the cookies

• Line two or more large rimmed baking sheets with parchment or, even better, anonstick baking mat such as a Silpat.
• Combine the almond flour and confectioners’ sugar in a food processor and pulse for 1minute. Sift the mixture through a fine-mesh strainer into a large bowl.
• Put the egg whites into the bowl of a stand mixer or in a mixing bowl. Put that bowl into another bowl filled with very hot water and warm the egg whites to between 90°F and 100°F. Add the cream of tartar. Remove the bowl from the water. Using the whisk attachment on the stand mixer or using a hand mixer, beat the egg whites on medium speed until there are stiff peaks when the mixer is stopped and the beaters are lifted. With the mixer running, slowly add the granulated sugar and continue to whip the whites until glossy. If adding food coloring, add up to 1/2 tsp. now, and beat briefly to combine.
• 添加杏仁粉混合物和使用large silicone spatula to fold it in until fully incorporated. Continue folding until batter dropped from the spatula sinks back into the batter as it levels itself; this will take at least a few minutes, and the batter’s volume will decrease.
• Transfer the batter to a large pastry bag fitted with a 1/2-inch plain tip. Pipe 2-inch circles spaced about 1 inch apart on the sheets. Rap the baking sheet against the counter a couple of times to pop any air bubbles and to flatten any peaks. Let sit at room temperature until no longer tacky; you should be able to touch them with a finger and leave no mark, 30 to 60 minutes.

• Position racks in the top and bottom thirds of the oven, and heat to 300°F. (If you have a convection oven, you’ll get the best results by setting the oven to 250°F on low convection.) Bake for 15 to 16 minutes on convection or 16 to 17 minutes in a regular oven, rotating the sheets and swapping their positions. The color won’t change, but they should have a nice “foot” and glossy tops. Transfer the baking sheets to racks and cool completely. Using an offset spatula, gently remove the cookies.

Make the filling

• In a 4-quart saucepan, whisk the cream and corn syrup over medium heat, swirling the pan a few times, until bubbles start to form around the edge, about 2 minutes. Remove from the heat, add the chocolate, and let sit for 30seconds. Slowly whisk the mixture until the chocolate is melted and smooth. Add the peppermint extract and whisk to combine. Let cool to room temperature, then cover and refrigerate the filling for up to 2 hours to firm up a bit before piping.
• Using a piping bag fitted with a 1/2-inch plain tip, pipe about 1 Tbs. of the filling onto the flat sides of half of the cookies. Top with another cookie of the same size to make a sandwich. Roll the cookies on their edge in the crushed candies so that the candy pieces adhere to the chocolate, sprinkling more on the chocolate, if necessary.
• Store the cookies in an airtight container at room temperature for up to 2 days.