Chocolate lava cakes (a.k.a. molten cakes or soufflé cakes) proved that fame can be damaging. The liquid-centered cakes, popularized by Chef Jean-Georges Vongerichten in the late ’80s, went viral for more than a decade until pastry chefs started to loathe them. But for chocolate-lovers, the dessert remains the apex, the acme, the epitome. If recipes could accept Hollywood stars, we’d give this one. Instead it will have to accept a permanent spot in our recipe box.
Special equipment: Parchment paper, used to line the ramekins for easy removal of the cooked cakes, can be purchased at most grocery stores.
Game plan: You can prepare the batter, place it in the ramekins, and refrigerate up to a day ahead. Let the ramekins sit at room temperature to take the chill off before baking. The batter can also be portioned into different-size ramekins, filled three-fourths full. The cooking times, however, will vary; just cook the cakes until the tops are no longer wet but still jiggle.
Heat the oven to 375°F and arrange a rack in the middle. Using 1 tablespoon of the butter, coat 8 (6-ounce) ramekins. Cut 8 rounds of parchment paper, each just large enough to fit in the bottom of a ramekin. Place a round in each ramekin. Cut 8 (2-1/2-by-10-inch) rectangle strips of parchment. Form 1 of the rectangles into a circle so its ends touch and place the strip flush along the inside of a ramekin; set aside. Repeat with the remaining rectangle strips and ramekins.
Place the chocolate in a large heatproof bowl. Melt the remaining 15 tablespoons of butter in a small saucepan over medium heat, stirring occasionally. Pour the butter over the chocolate and whisk until smooth and melted. Whisk in the Cognac and vanilla; set aside.
Place the sugar, egg yolks, and salt in a large bowl and, using a clean whisk, whip until lightened in color and the sugar is nearly dissolved. Pour the mixture over the melted chocolate and fold together using a rubber spatula until just combined; set aside.
Using a stand mixer fitted with a whisk attachment or a clean whisk and a large clean bowl, whisk the egg whites to medium-stiff peaks, adding the cream of tartar when the eggs just start to foam. Alternate folding the whipped egg whites and flour, in three additions, into the chocolate mixture until just combined (a few remaining streaks are OK; do not overmix). Divide the batter among the ramekins (each about three-fourths full) and place them on a baking sheet. Bake until the sides of the cakes have set and the tops are no longer wet but the very center (about 1 inch’s worth) still jiggles, about 10 to 12 minutes. Transfer the ramekins to a wire rack and cool for 5 minutes.
If serving with raspberry coulis, spoon a pool of the sauce on each of 8 plates. Slowly remove the parchment paper collar from each cake, gently pressing on the cake to keep it in place as you remove the collar. Using an oven mitt or dry towel to protect your hands, invert a warm cake onto a pool of raspberry coulis. Remove the parchment paper round from the bottom. Repeat with the remaining cakes. If you choose, dust each cake with powdered sugar and serve warm with vanilla ice cream.