One-Bowl Flourless Chocolate Cake with a Truffle Center

By Sprig Originals ✓ · cooked up in Sprig

A dense, glossy chocolate cake built in a single bowl over a pot of simmering water — no mixer, no flour, no fuss. A water bath keeps the custardy edges silky while the center stays deliberately underbaked, so the middle sets into something closer to truffle ganache than cake. Good bittersweet chocolate is the whole recipe, so buy the bar you'd happily eat on its own.

Ingredients

• 10 oz bittersweet chocolate (66–72%), coarsely chopped
• 10 tbsp unsalted butter, cut into pieces, plus more for the pan
• 3/4 cup granulated sugar
• 3 tbsp unsweetened cocoa powder (Dutch-process preferred)
• 1 tsp instant espresso powder
• 3/4 tsp kosher salt
• 2 tsp vanilla extract
• 5 large eggs, at room temperature

• 3/4 cup heavy cream, cold
• 1/4 cup crème fraîche or sour cream
• 2 tsp powdered sugar
• flaky sea salt, for finishing
• fresh raspberries (optional)

Instructions

1. Heat the oven to 325°F with a rack in the lower-middle position. Butter a 9-inch round cake pan (2 inches deep) generously, line the bottom with a parchment round, and butter the parchment. Wrap the outside bottom and sides of the pan tightly in a double layer of heavy-duty foil — this is your insurance against water seeping in. Set the pan inside a roasting pan or 9x13 baking dish and put a kettle of water on to boil.
2. Bring 1 inch of water to a bare simmer in a medium saucepan. Set a large heatproof bowl over it (bottom not touching the water) and add the chopped chocolate and 10 tablespoons butter. Stir occasionally with a flexible spatula until fully melted and smooth, 4 to 6 minutes. Remove the bowl from the heat.
3. Whisk the sugar, cocoa powder, espresso powder, and kosher salt directly into the warm chocolate until the mixture is thick, glossy, and no cocoa lumps remain. Whisk in the vanilla. Let it cool for 3 to 4 minutes — it should feel warm, not hot, on the back of your finger.
4. Add the eggs one at a time, whisking just until each disappears into the batter before adding the next. Stop the moment the batter is uniform and satiny; whisking in extra air here causes the cake to dome and crack. Scrape the bowl once to catch unmixed streaks at the bottom.
5. Pour the batter into the prepared pan and smooth the top. Rap the pan gently on the counter 3 or 4 times to release large bubbles. Pull the roasting pan into the oven partway on the rack, then pour boiling water into the outer pan until it comes 1 inch up the sides of the cake pan. Slide the rack in and close the oven.
6. Bake 30 to 36 minutes. You want the outer 2 inches puffed and set with a thin matte crust, and a 3-inch circle in the very center that still wobbles as a single soft mass when you nudge the pan. A thermometer in the middle should read 160–165°F; a toothpick 1 inch from the edge comes out with thick fudgy batter clinging to it. Err on the early side — this is the truffle center.
7. Carefully lift the cake pan out of the water bath, peel off the foil, and cool on a rack for 1 hour. The center will sink slightly and firm up as it cools. Refrigerate, uncovered, for at least 3 hours or up to 2 days to fully set the crumb.
8. Thirty minutes before serving, run a thin knife around the edge, set the pan directly on a low burner or in 1 inch of hot tap water for 30 seconds to loosen the butter, then invert onto a plate, peel off the parchment, and flip right side up onto a serving plate. Let the cake sit at room temperature — it should be cool but no longer fridge-cold.
9. Whip the cold cream, crème fraîche, and powdered sugar to soft peaks. Dip a thin knife in hot water and wipe it dry between every slice. Cut into 10 wedges, add a spoonful of cream, a few flakes of sea salt, and raspberries if you like.

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