Preheat oven to 425 degrees and grease 4 (6 ounce) ramekins, place on baking sheet. In a large microwavable bowl microwave butter and chocolate for 1 minute or until butter is melted, stir until chocolate is completely melted.
Stir in powdered sugar until well blended. Whisk in eggs and egg yolks, then stir in flour. Divide batter between prepared ramekins. Bake for 13 to 14 minutes or until sides are firm but centers are soft. Let stand for 1 minute.
Run a small knife around the cakes to loosen, invert cakes onto plates. Top with whipped cream and serve immediatley.