Bloom the gelatin in a small bowl of cold water for about 5 minutes. In a saucepan over low heat, combine espresso, brown sugar, ground spices, and gelatin. Stir until dissolved, then add white chocolate, stirring until melted and smooth. Let cool to room temperature.

Whip the mascarpone and heavy cream using an electric mixer until soft peaks form (about 3–5 minutes). Fold in the cooled espresso mixture gently, maintaining airiness.

Mix flour, spices, molasses, softened butter, and egg yolk until a soft dough forms. Roll out to ¼ inch thick and cut circles for silicone molds. Bake at 350°F (175°C) for 10-12 minutes until firm but not overly browned.

Fill silicone dome molds three-quarters full with mousse, pressing a cookie circle into each mold. Freeze for at least 6 hours or overnight.

Prepare the mirror glaze according to recipe instructions at about 90°F (32°C). Unmold mousse domes and pour glaze over them evenly.

Let the glazed domes set in the fridge for about 30 minutes before serving. Garnish with cocoa or mini gingerbread cookies.