Lightly sprinkle unsweetened cocoa over interiors; shake out excess.
Set cups on baking sheet.
In microwave safe bowl, combine chocolate and butter.
Microwave on medium 1-3 minutes or until almost melted.
Stir until smooth.
With whisk, beat eggs, egg yolks, 1/2 cup sugar and beer in large bowl until well blended.
Stir in chocolate mixture.
Stir in flour until thoroughly blended.
Divide mixture evenly into custard cups (filled cups can be held in refrigerator for up to 2 hours before baking).
In another large bowl, beat all cream ingredients at medium-high speed until stiff peaks form.
When ready to serve, bake cakes on baking sheet 12-13 minutes or until tops are dry and outside edges just begin to pull away from edge of cups (centers may be slightly sunken but will rise as they sit).
Place on wire rack; cover loosely with foil.
Let stand 4 minutes.
With hot pad or towel, hold each cup and run knife around edges to loosen cakes; unmold hot cakes onto serving plates.