Line an 8×8-inch pan with parchment paper and lightly spray with nonstick spray. Spraying a little under the parchment helps keep it in place.

In the bowl of a stand mixer, sprinkle the gelatin over ½ cup cold water. Let it bloom while you prepare the syrup.

In a medium saucepan over medium heat, combine the granulated sugar, corn syrup, salt, peppermint flavoring, broken candy canes, and ½ cup water. Stir until the sugar dissolves, then stop stirring and increase the heat to bring the mixture to a boil.

Allow the syrup to boil without stirring until the bubbles slow and begin to pop gently, or until a candy thermometer reads 220°F. This usually takes about 8–10 minutes.

Remove the syrup from the heat. With the mixer running on low speed, slowly pour the hot syrup into the softened gelatin.

Once all the syrup has been added, gradually increase the mixer speed to high. Beat for 8–10 minutes, until the mixture turns white, thick, and nearly triples in volume.

Add the peppermint extract (if using) and beat on high for 1 more minute.

Scoop out about ¼ cup of the marshmallow mixture and tint it red with the food coloring.

Pour the white marshmallow mixture into the prepared pan. Drop spoonfuls of the red mixture randomly over the top, then gently swirl with a knife or rubber spatula to create a marbled effect.

If the marshmallow mixture becomes difficult to spread, microwave it for 15–20 seconds to soften.

Let the marshmallows set uncovered at room temperature for at least 8 hours.

To Cut

Dust a cutting board with about 1 tablespoon powdered sugar. Place the remaining powdered sugar in a small bowl.

Remove the marshmallows from the pan and cut into squares using a sharp knife. Toss each piece lightly in powdered sugar to prevent sticking.