Preheat the oven to 375 degrees. Spray a cake pan with nonstick cooking spray and line with parchment paper. Set aside.
In a microwave-safe bowl, melt chocolate and butter together, stirring every 20-seconds. Once completely melted and smooth, stir in sugar and vanilla. Then one at a time, mix in the eggs. Sift cocoa powder into the batter with a sprinkling of salt and gently stir.
Pour batter into the prepared cake pan. Smooth the top and bake 20-25 minutes. Serve warm without whipped cream or cool completely before topping.
For the Whipped Cream
Whip all ingredients together until stiff. Top cooled caked with whipped cream and slivered almonds.