Flourless Chocolate Cake

Before you start

A flourless chocolate cake has only a few ingredients: good dark chocolate, butter, sugar and eggs. The eggs are whipped with sugar to add a little lift, then folded into melted chocolate and butter. In the oven the cake rises gently and sinks as it cools into a dense, fudgy torte with a crisp, thin top crust and a truffle-like center.

Because chocolate gives most of the flavor and all of the structure, the quality of your chocolate matters more than in any other cake. Choose a bar in the 60 to 70 percent cacao range. Bake it gently and stop when the center still looks slightly soft, but has reached a safe temperature for eggs. The cake firms further as it cools and is easier to slice after a rest.

Ingredients

• 225 g (8 oz) bittersweet chocolate, 60 to 70% cacao — chopped
• 170 g (¾ cup) unsalted butter — cut into pieces
• 5 large eggs — room temperature
• 150 g (¾ cup) granulated sugar
• ½ tsp fine salt
• 1 tsp vanilla extract
• 1 tsp instant espresso powder — optional; deepens the chocolate flavor
• 2 tbsp cocoa powder — for dusting the pan and serving

Method

1. Heat the oven to 160°C (325°F). Grease the springform, line the bottom with parchment and dust the sides with cocoa. Wrap the outside in two layers of heavy-duty foil.
2. Melt the chocolate and butter together in a bowl set over barely simmering water, stirring until smooth. Remove from the heat and stir in the salt, vanilla and espresso powder. Let it cool for 5 minutes.
3. Whip the eggs and sugar on high speed for 5 to 6 minutes, until pale, thick and about doubled in volume.
4. Fold one-third of the egg foam into the chocolate to lighten it, then fold in the rest in two additions until no streaks remain.
5. Pour the batter into the pan and smooth the top. Set it in the roasting pan and pour in hot water to come about 2.5 cm (1 in) up the sides.
6. Bake for 45 to 55 minutes, until the edges are puffed and set and the center looks matte with a slight wobble. An instant-read thermometer in the center should read 71°C (160°F).
7. Lift the pan out of the water and cool on a rack for 2 hours; the cake will sink and the top may crack, which is normal. Run a knife around the edge, release the ring and dust with cocoa before slicing with a hot, dry knife.

Tips for success

• Do not let the melted chocolate get hot. Above about 50°C (120°F), it can scramble the eggs as you fold them in.
• Serve thin slices with lightly sweetened whipped cream or berries to cut the richness.
• The cake tastes even better the next day, once the flavors settle.

Substitutions

Butter

Use coconut oil for a dairy-free torte. The texture is a bit firmer when chilled and the cake has a faint coconut note unless you use refined oil.

Granulated sugar

Light brown sugar gives a deeper caramel flavor and a slightly moister, denser center.

Bittersweet chocolate

Semisweet chocolate (about 50 to 55%) makes a sweeter, milder cake; cut the sugar to 120 g.

Variations

Orange flourless cake

Add the finely grated zest of 1 orange to the melted chocolate and serve with orange segments.

Raspberry torte

Scatter 125 g fresh raspberries over the batter before baking; they sink slightly and add tart pockets.

Troubleshooting

Cake is oily on top

The chocolate mixture was too hot or the butter separated. Melt gently and let it cool slightly before folding in the eggs.

Center is wet and sticky after cooling

It came out too early. Bake until the center reaches 71°C (160°F) even if it still looks a little soft.

Texture is dry and crumbly

It overbaked or the oven ran hot. Check the temperature with an oven thermometer and start testing at 45 minutes.

Storage

Cover and keep at room temperature for 1 day or refrigerate for up to 5 days. Bring slices to room temperature before serving for a softer texture. Wrapped well, the cake freezes for up to 2 months.

Safety notes

Bake until the center reaches 71°C (160°F), the FDA guidance for egg dishes. The recipe has no wheat flour, but check chocolate and cocoa labels if you bake for someone with celiac disease. Contains egg and milk.