1 stick (4 oz.) unsalted butter
6 oz. bittersweet chocolate, preferably Valrhona
2 egg yolks
1/4 c sugar
pinch of salt
2 TBS all-purpose flour
1. Preheat the oven to 450 degrees F. Butter and slightly flour four 6 oz. ramekins. Tap out the excess flour. Set the ramekins on a baking sheet.
2. In a double boiler, over simmering water, melt the butter with the chocolate. In a medium bowl, beat the eggs, with the egg yolks, sugar, and salt at a high speed until thickened and pale.
3. Whisk the chocolate until smooth. Quickly fold it into the egg mixture along with the flour. Spoon the batter into the prepared ramekins and bake for 12 minutes, or until the sides of the cakes are firm but the centers are soft. Let the cakes cool in the ramekins for 1 minute, then cover each with an inverted dessert plate. Carefully turn each one over, let stand for 10 seconds and then unmold. Serve immediately.