Place the dark chocolate chips in a microwave-safe bowl. Heat in 20-second intervals, stirring after each, until the chocolate is fully melted and smooth. Alternatively, melt the chocolate using a double boiler over simmering water, stirring frequently. Set aside to cool slightly.
In a clean mixing bowl, add the heavy cream, powdered sugar, and vanilla extract. Using an electric mixer or a whisk, beat until stiff peaks form. The cream should hold its shape firmly when you lift the whisk.
Once the melted chocolate has cooled but is still pourable, stir in the peppermint extract. Mix until evenly incorporated.
Gently fold one-third of the whipped cream into the chocolate mixture to lighten it. Then fold in the remaining whipped cream carefully to maintain the mousse’s airy texture. Be gentle to keep the mousse fluffy and light.
Spoon or pipe the mousse into your serving cups or ramekins. Tap the cups lightly on the counter to release any air bubbles. Refrigerate the mousse cups for at least 2 hours or until set.
Before serving, sprinkle crushed peppermint candies over the top for a festive finish.
