I'm posting another repeat for the holidays because this is so easy and so good, you need a kick in the ass for not making it at least once.
CakeOne box of chocolate cake mix. Follow the directions on the box, dummy. I recommend a greased 13x9 pan.
A small can of sweetened condensed milk
A small can of evaporated milk
Half a pint of heavy whipping cream.
Mix the milk in a bowl and leave in the refrigerator.
Bake the cake and set it aside to cool. After it's cooled (don't want it falling apart!), turn it out onto a cutting board right side up. I used a small cutting board and the lid for my cake pan to sandwich the cake together for flipping. Trim the top of the cake until its level with the sides. I use a bread knife for this, and its an easy way to shape a cake. Keep both ends of the knife on top of the crusty edges of the cake and draw it across the top, leveling the cake flat. Enjoy the trimmings.
Turn the cake back into the pan upside down. Poke with holes and pour the milk over your cake. Cover and set in the refrigerator overnight (about 12 hours).
MousseThis isn't really mousse, but it's a whole lot easier than the other mousse recipe I was using. Whip one cup of sugar into one cup of heavy whipping cream until stiff and put back in the refrigerator. Meanwhile, melt four ounces of chocolate (I used the expensive stuff) over a double boiler. If you don't know what a double boiler is, its a medium-sized pot filled halfway with water and heated to simmering and a saucepan set over the top to cook in. Let the chocolate cool for 15-20 minutes. Mix 1/4 of the whipped cream into the chocolate, and fold that into the remaining whipped cream gently.
After your cake has set for a few hours, spread the chocolate mousse topping over the cake. Chill overnight and serve. You'll be glad you did.