6 Tbsp. unsalted butter
8 oz. semisweet chocolate, chopped
2 large eggs
2 large egg yolks
1⁄3 C. sugar, plus additional sugar
1 Tbsp. coffee liqueur, plus additional liqueur
1⁄3 C. all-purpose flour
1⁄2 C. heavy cream
Preheat the oven to 400°F. Heavily butter and lightly flour six 4-6 oz. ramekins. Knock out the excess flour.
In a double boiler over simmering water, melt the butter and chocolate. Remove from the heat and set aside.
In a large bowl, whisk together the eggs, egg yolks, and the 1⁄3 C. sugar. Stir in the 1 Tbsp. coffee liqueur. Whisk in the chocolate mixture, then fold in the flour. Divide the batter evenly among the ramekins. Place the ramekins on a baking sheet and bake until firm at the edges and glossy and barely set in the center, 9 to 11 minutes. Remove from the oven and let cool for 10 minutes in the pan.
In a deep bowl, beat the cream until soft peaks form. Add additional sugar and coffee liqueur to taste.
Run a sharp knife around the edges of the cakes to loosen them. Invert each cake onto one of 6 small plates and top each with a dollop of the whipped cream.