Recipe: Rich Hot Chocolate Cake (baked in mugs or springform pan)

This came from the recipes I cut this morning from old Real Simple Magazine. Sounds like just the ticket for those upcoming chilly nights!

RICH HOT CHOCOLATE CAKE
(baked in mugs or a springform pan)

8 Tablespoons (1 stick) unsalted butter, plus extra for coating
3 Tablespoons flour, plus extra for dusting
1/2 cup sugar, plus extra for dusting
10 ounces semisweet chocolate, coarsely chopped
4 large eggs
1 large egg yolk
1 teaspoon vanilla
1/4 teaspoon salt
1/2 cup mini marshmallows
2 Tablespoons unsweetened cocoa powder

Preheat oven to 375 degrees F. Generously butter, flour and sugar eight 6-inch coffee cups or mugs made of ovenproof stoneware. (or eight 6-ounce ramekins) Wipe the rims clean.

Place the 8 Tablespoons of butter and the chocolate in a medium heatproof bowl over a pan of simmering water (or use a double boiler) and melt, stirring once or twice until smooth. Remove from heat and let cool 5 minutes.

Using a handheld mixer, beat the eggs, yolk, vanilla, salt and 1/2 cup sugar at the highest speed until the volume doubles and the mixture becomes foamy, about 5 minutes.

Stir the 3 Tablespoons of flour into the chocolate, then gradually add it to the egg mixture, beating on low until it's fully incorporated. Ladle the batter into each cup until it's about 1/2 inch from the rim.

Bake until the cakes puff and begin to crack but the centers are still a bit runny, 13 to 17 minutes. Remove from oven.

Sprinkle with marshmallows, then return to oven for 2 to 4 minutes, until the marshmallow tops begin to crisp. Remove from oven; let cool about 5 minutes.

Sift eh the cocoa on top.

TO MAKE IN SPRINGFORM PAN:
Use enough regular-size marshmallows to cover. Increase the initial baking time to 22 to 25 minutes or, if you prefer a more gooey center, to 17 to 20 minutes.