INGREDIENTS

For the Cake

6 oz Brazil 43% chocolate divided (3 oz for cake, 3 oz for ganache)

STEP BY STEP

Prepare the Pans

Position a rack in the center of the oven and preheat to 350°F (175°C). Generously butter two round cake pans and line the bottoms with parchment paper circles. Butter the parchment and dust the pans lightly with flour, tapping out any excess.

Make the Chocolate Base

Chop 3 ounces of the Brazil chocolate into small, even pieces. Place in a heatproof bowl set over a pot of barely simmering water (the bowl should not touch the water). Add the butter cubes and hot espresso. Stir occasionally until completely melted and smooth, about 5 minutes. Remove from heat and set aside to cool slightly—the mixture should be warm to the touch but not hot.

Baker’s Note: If the chocolate is too hot when added to the eggs, it will cook them. Patience here ensures a silky batter.

Whip the Eggs

In the bowl of a stand mixer fitted with the whisk attachment (or using a hand mixer and large bowl), combine the eggs and sugar. Beat on high speed for 8 to 10 minutes, until the mixture has tripled in volume, turned very pale yellow, and falls from the beaters in thick, slowly dissolving ribbons. This vigorous beating is what gives the cake its remarkably light texture despite the modest amount of flour.

Fold It Together

Gently fold about one-third of the whipped egg mixture into the warm chocolate mixture to lighten it. Pour this chocolate mixture back into the remaining egg mixture. Using a large rubber spatula, fold together with broad, sweeping strokes, turning the bowl as you work. When nearly combined, sift the flour over the batter and continue folding just until no streaks remain. The batter should be glossy and mousse-like. Work with a light hand—overmixing will deflate the eggs and result in a dense cake.

Bake

Divide the batter evenly between the prepared pans and smooth the tops. Tap each pan gently on the counter two or three times to release any large air bubbles. Bake for 25 to 30 minutes, rotating the pans halfway through, until the cakes spring back when lightly touched and a toothpick inserted into the center emerges with a few moist crumbs clinging to it.

Cool the cakes in their pans on wire racks for 10 minutes. Run a thin knife around the edges, then invert onto the racks. Peel away the parchment and turn the cakes right-side up. Allow to cool completely before assembling, at least 30 minutes.

Baker’s Note: Warm cake will melt the dulce de leche and ganache. Resist the temptation to assemble early.

Make the Ganache

While the cakes cool, finely chop the remaining 3 ounces of Brazil chocolate. In a small saucepan, heat the cream until small bubbles form around the edges—do not let it boil. Pour the hot cream over the chopped chocolate and let stand without stirring for 2 minutes. Starting from the center and working outward, stir gently until the mixture is perfectly smooth and glossy. Stir in the tablespoon of butter, if using. Set aside at room temperature to thicken slightly, about 15 to 20 minutes. The ganache should be thick enough to spread yet still pourable.

Assemble

If the cake tops are domed, use a long serrated knife to level them, creating flat surfaces. Place one layer on your serving plate. Spread the dulce de leche evenly over the top, leaving a scant ½-inch border around the edge. Gently place the second layer on top, pressing down very lightly.

Spread a thin layer of ganache over the entire cake—top and sides. This “crumb coat” seals in any loose crumbs. Refrigerate for 10 minutes to set.

Remove the cake from the refrigerator. Pour the remaining ganache over the top, using an offset spatula to coax it to the edges, allowing it to cascade naturally down the sides. Smooth the sides with the spatula, or embrace the dramatic drips for a more rustic presentation.

Let the cake stand at room temperature for 15 minutes to allow the ganache to set, or refrigerate for 10 minutes if you’re pressed for time.

To serve

Slice with a hot, dry knife, wiping the blade clean between cuts. Serve at room temperature with strong coffee or café con leche. The cake keeps, covered, at room temperature for up to 3 days, or refrigerated for up to 5 days. If chilled, allow it to come to room temperature before serving for the fullest flavor.