Preheat the oven to 450°F (232°C). Butter four (four-ounce) ramekins, then dust with cocoa powder, coating the bottom and sides. Assertively tap out excess to form a thin layer of cocoa powder. Place ramekins on a sheet tray.
cocoa powder
In a heatproof glass bowl set over a small saucepan of simmering water (do not let bowl touch water), melt butter, chocolate, and espresso powder, stirring until smooth, about ten minutes. Remove from heat and stir in vanilla. Let cool slightly.
4 ounce unsalted butter, 6 ounce dark chocolate, ½ teaspoon espresso powder, 1 teaspoon vanilla extract
In the bowl of a stand mixer fitted with the whisk attachment, beat eggs, egg yolk, sugar, and salt on medium-high speed until doubled in volume, pale, and fluffy, four to five minutes.
3 large egg, 1 large egg yolk, ¼ cup sugar, ½ teaspoon kosher salt
Whisk flour into the chocolate mixture. Gently fold the chocolate mixture into the egg mixture, being careful not to deflate.
2 tablespoon all-purpose flour
Divide the batter evenly among each ramekin. Then bake for nine to ten minutes, until cakes are risen, sides spring back when touched, and centers still jiggle slightly. Rest cakes in the ramekins for one minute.
To unmold: Place a small plate over each ramekin, wearing an oven mitt, invert quickly but gently, and let sit for ten seconds before lifting the ramekin off.
Dust the cakes with powdered sugar, garnish with mint, and serve with raspberry coulis and whipped cream.
powdered sugar, fresh mint sprigs