Rich brownie on the bottom and decadent chocolate mousse topping!

Brownie Bottom: 4 TBS butter 1/2 cup sugar 1/4 cup + 2 TB  cocoa powder 1/4 t salt 1/2 t vanilla  1  egg 1/4 c  flour

Chocolate Mousse: 1  egg 2 TB  sugar 1 c  heavy  cream 1/2 t vanilla  3 oz chocolate

Microwave butter with sugar and cocoa powder.  Stir salt and vanilla to cooL.  Stir mixture to cool butter. 

Add egg. Add flour.  Scrape mixture into prepared pan, and  bake on a sheet pan at 325° for 25 minutes. 

Beat egg and sugar until pale yellow Add cream. Pour into a saucepan over medium heat. Stir constantly  until mixture thickens. 

Add chopped chocolate to pan for 1 minute. Remove the lid, and whisk until  chocolate is dissolved. Pour mixture into a bowl and chill for an hour until firmed up.

Beat remaining cream.  Remove chocolate mixture from fridge,  and break in to pieces.  Add them to the bowl while beating.  Scrape mousse on brownie in the pan and refrigerate.

To Serve, slice cake into 4-6 even slices, top with  shaved chocolate or  truffles and serve.