Step 1

In a medium saucepan, whisk the sugar and eggs together over low heat. Cook, whisking frequently, until mixture reaches 75 C. Remove from heat.

Step 2

In a small metal bowl over a bowl of simmering water, melt the semisweet chocolate, stirring often.

Step 3

Whisk the melted chocolate and vanilla into the sugar and egg mixture. Set aside and let cool slightly.

Step 4

Meanwhile, in a large bowl, beat the butter until light and fluffy. Beat in the chocolate mixture. Beat at high speed for 4-5 minutes or until light and fluffy. The colour of the mixture should lighten. Set aside.

Step 5

In another large bowl, whip the heavy cream until soft peaks form. Add the icing sugar and beat until stiff.

Step 6

Fold the whipped cream into the chocolate mixture until blended.

Step 7

Spoon the chocolate mousse into glass bowls, ramekins, or other serving dish. You can spoon the mousse into separate bowls or into one large bowl. Chill the mixture for 4-6 hours. When ready to serve, make the topping.

Step 8

In a large bowl, beat the heavy cream until soft peaks form. Add the icing sugar and beat until stiff.

Step 9

Dollop the cream over the chocolate mousse.

Step 10

Sprinkle the oreo cookie crumbs over the whipped cream. Serve within an hour.