01 - Gently heat 1 cup heavy cream in a small saucepan until just simmering. Remove from heat and stir in chopped white chocolate until fully melted and smooth.
02 - Whisk in powdered sugar and peppermint extract into the mixture. Allow to cool slightly, then refrigerate for 30 to 45 minutes until chilled.
03 - Whip the chilled mixture using an electric mixer or hand whisk until soft peaks form. Divide evenly into four serving glasses or ramekins.
04 - Heat 1/3 cup heavy cream in a small saucepan until just simmering. Remove from heat and add chopped dark chocolate, stirring until smooth and glossy.
05 - Let ganache cool for 5 minutes, then spoon evenly over the peppermint cream layers in each serving glass.
06 - Refrigerate the assembled layers for at least 1 hour to set before serving.
07 - Optionally, garnish with fresh mint leaves and chocolate shavings just before serving.