Preheat oven to 450°. Spray bottoms and sides of six-ounce silicone or custard cups, spray with cooking spray that has flour in it and then dust with cocoa and sprinkle optional shredded coconut.
Melt chocolate, butter and vanilla over low heat in a small saucepan, stirring often. Cool a little before pouring into cake mixture.
Beat eggs and egg yolks in a large mixing bowl with electric mixer or wire whisk until well blended. Beat in 2-cups of powdered sugar. Beat in melted chocolate mixture and flour. Place prepared baking cups on cookie sheet with sides so they don't slide off placing them in and out of the oven. Divide batter evenly among cups.