Preheat oven to 400 degrees. Adjust rack to center of oven.
Melt chocolate and butter in top half of double boiler set over
simmering water. Keep warm. In separate double boiler, whisk
eggs until warm. Remove eggs from double boiler, place into
mixer, and whip on high until eggs double in bulk. Remove bowl
from mixer. By hand, fold warm melted chocolate and butter into
eggs. Pour into heart-shaped baking pan or individual heart
molds. Bake at 400 degrees in a water bath for approximately
20 minutes. Serve warm, either directly in pan or in molds.
Top with whipped cream and fresh berries.