Melt butter in a small saucepan over low heat. Add sugar and stir well. Remove from heat, let cool slightly, then quickly whisk in the beaten eggs and whiskey. Put the sauce back on the stove over low heat and whisk constantly until the sauce has thickened slightly. (If it's overcooked, the sauce will curdle.) Keep the sauce warm until serving.
NOTE: This sauce contains egg yolks which can carry salmonella bacteria if not fully cooked. As with other foods like beef tartare, Caesar salad or eggs cooked "sunny side up", caution is advised when eating raw or lightly cooked eggs.Makes 4 Source: