Preheat oven to 350 degrees Fahrenheit. Grease a nine-inch round pan and set aside.
In the bowl of an electric mixer, beat egg whites until frothy. Slowly add granulated and vanilla sugars and beat until stiff peaks form.
In a double boiler, heat margarine or oil with chocolate, stirring occasionally until chocolate is melted and smooth. Set aside to cool.
In the bowl of an electric mixer, whisk cooled, melted chocolate into egg yolks.
By hand, gently fold egg whites into the chocolate mixture.
Set aside one and a half cups of mousse.
Pour remaining mousse into the prepared pan. Bake 45 minutes, then let cool 30 minutes.
Once cool, top with reserved (unbaked) mousse. Freeze to set, about three hours.
While the mousse sets, line a baking sheet with parchment paper.
Melt bars of baking chocolate in a double boiler.
Pour melted chocolate onto the prepared baking sheet and sprinkle with coconut, nuts, and dried cranberries. Refrigerate until hardened.
Break into pieces and store in the fridge in an airtight container.
Just before serving, garnish with whipped topping (beat in an electric mixer until stiff peaks form), chocolate bark, chocolate shavings, and/or crushed nuts. Use as many garnishes as you like!
To make chocolate shavings, simply “peel” the side of a cold chocolate bar with a vegetable peeler.