Chocolate Volcano Cakes

        Individual Chocolate Volcano Cakes
            Serves 8

2 T flour
8 T (1 stick) unsalted butter, cut into 4 pieces
2 oz. unsweetened chocolate and
6 oz. semi-sweet chocolate, chopped coarse
4 large eggs, plus 1 egg yolk
1 tsp vanilla
¼ tsp salt
½ cup granulated sugar
    Powdered sugar or unsweetened cocoa for dusting the cakes (optional)
    Whipped cream for serving (optional)

Adjust an oven rack to the middle position and heat the oven to 400 degrees.  Generously grease and flour eight 6-oz ramekins or heatproof glass baking cups; tap out the excess flour and position the ramekins in a shallow roasting pan or on a rimmed baking sheet.  Meanwhile, melt the butter and chocolate in a medium heatproof bowl set over a pan of almost-simmering water, stirring once or twice, until smooth; remove from the heat.

Beat the eggs, yolk, vanilla, salt, and granulated sugar in the bowl of a standing mixer set at the highest speed until the volume nearly triples, the color is very light and the mixture drops from the beaters in a smooth, thick stream, about 5 minutes.  Scrape the egg mixture over the melted chocolate and butter; sprinkle the flour over the egg mixture.  Gently fold the egg and flour into the chocolate until the mixture is a uniform color.  Ladle or pour the batter into the prepared ramekins.  (The ramekins can be covered lightly with plastic wrap and refrigerated for up to 8 hours.  Return to room temperature for 30 minutes before baking.)

Bake until the cakes have puffed about ½ inch above the rims of the ramekins, have a thin crust on top, and jiggle slightly at the center when the ramekins are shaken very gently, 12-13 minutes.  Run a paring knife around the inside edges of the ramekins to loosen the cakes and invert onto serving plates; cool for 1 minute and lift off the ramekins.  Sieve a light sprinkling of powdered sugar over the cakes to decorate, if desired, serve immediately with whipped cream, if using.