Preheat your oven to 350°F (175°C). In a mixing bowl, combine crushed chocolate graham crackers, melted butter, and granulated sugar until well blended. Press this mixture firmly into the bottom and up the sides of a tart pan. Bake for 10 minutes or until the crust is set and slightly golden. Allow it to cool completely before filling.

In a small bowl, sprinkle unflavored gelatin over cold water and let it sit for 5 minutes. Microwave the mixture for about 15 seconds until the gelatin dissolves. Allow this to cool slightly.

Melt white chocolate over low heat in a saucepan, stirring continuously until smooth. Remove from heat and whisk in milk, the prepared gelatin, and peppermint oil. Let the mixture cool to below 85°F.

In a large mixing bowl, whip the heavy cream with powdered sugar until medium-stiff peaks form. Gently fold the whipped cream into the cooled chocolate mixture.

Spoon the mousse into the cooled crust and smooth the top. Cover with plastic wrap and refrigerate for several hours or overnight.

Heat cream until boiling, then stir in bittersweet chocolate until smooth. Mix in light corn syrup and warm water. Cool slightly before applying.

Pour the glaze over the mousse layer, ensuring an even coat. Allow to set at room temperature for about 1 hour.