- Line a 22.5-cm (9-in) square pan with parchment paper and set aside.
- Begin meringue preparation. Pour maple syrup and orange juice into a heavy-bottom saucepan. Boil over medium heat until a candy thermometer reads 115 °C (240 °F).
- Meanwhile, beat egg whites, cream of tartar and salt in a stand mixer at medium speed, until soft peaks form.
- As the whites take form, mix the gelatin and water in a bowl. Let stand 5 minutes and set aside.
- When syrup reaches 115 °C (240 °F) on the candy thermometer, reduce mixer speed and continue to beat whites while drizzling with half the syrup.
- Add remaining hot syrup to the gelatin and stir well to dissolve.
- Beat this mixture with an electric mixer until it becomes a mousse.
- Combine mousse and meringue in the mixer, increase speed and beat 5 to 7 or until the meringue is lukewarm and forms very stiff peaks.
- Pour into the prepared pan and cover with plastic wrap.
- Refrigerate for 2 hours.
- Cut marshmallow into 12 cubes and roll in maple sugar.
Refrigeration Time: 2 hours
These marshmallows keep for one week in an airtight container at room temperature.