Gâteau Chocolat

Ingredients

• 425 g (3 and 3/4 sticks) unsalted butter, plus extra for greasing
• 675 g single-origin chocolate, around 70% (1 1/2 pounds)
• 500 g eggs, at room temperature (about 10 large eggs, chalazas removed)
• 575 g organic cane sugar (2 1/2 cups)
• 1/8 tsp salt

Method

1. Preheat the oven to 120°C (250°F). Position the oven rack in the middle of the oven.
2. Butter a 23 cm (23 cm (9 in)) springform pan all along the bottom and sides. Cut out a parchment circle the size of the bottom and line the pan. (If the pan tends to leak, make the parchment slightly larger and press over the seam to seal.)
3. Place the springform pan in the center of a half-sheet baking tray. Set aside.
4. Boil a liter of water.
5. Crack open all the eggs and remove the chalazas.
6. Cut the butter into cubes and place it in a 4-quart saucepan.
7. Chop the chocolate and add it to the saucepan with the butter.
8. Heat the butter and chocolate over very low heat. Once the butter begins to melt, stir constantly to keep the chocolate from scorching and seizing. Once fully melted and smooth, turn off the heat and set aside.
9. Using a stand mixer, mix the eggs on low to break them up, then increase to medium-low.
10. Slowly stream the sugar into the eggs as they whip. Once all the sugar is added, whip on medium-high until the mixture quadruples in volume (about 10 minutes at room temperature, 20 if cold).
11. During the last 2 minutes of whipping, check the butter and chocolate mixture. Rewarm if the chocolate has started to harden. Stir to ensure it is smooth.
12. Once the eggs are ready, reduce the mixer speed to medium-low. Stream in the chocolate mixture very slowly so the chocolate emulsifies into the eggs.
13. Add the salt and whip until all the chocolate is incorporated with no streaks.
14. Remove the bowl from the mixer and stir 2-3 times with a silicone spatula to ensure everything is incorporated. Tap the bowl on the counter to release air bubbles.
15. Pour the batter into the prepared pan.
16. Place the tray with the springform pan on the middle rack. Carefully pour the liter of boiling water into the tray, creating a water bath.
17. Bake for 2 hours. After 2 hours, gently move the tray back and forth to check doneness — the cake should have a slight jiggle in the center or none at all. If very jiggly, bake an additional 10-15 minutes. Remove carefully to avoid spilling water.
18. Cool in the pan for about 30 minutes, then lift the springform pan onto a wire rack to cool completely.
19. Run a paring knife around the edge to release from the ring. (Leave on the base.) Wrap and chill in the fridge for at least 6 hours, preferably overnight.
20. To slice, run a chef's knife under hot tap water, wipe dry, and cut. Rinse and dry the knife between each cut.
21. Garnish with whipped cream, toasted hazelnuts, strawberries, or raspberries if desired.
22. The gateau can be eaten cold, but coming to room temperature for about 20 minutes gives the best texture and flavor.

Tips

• A 23 cm (23 cm (9 in)) springform pan about 7-8 cm (8 cm (3 in)) deep is needed.
• Do not skip the water bath; it bakes the gateau gently and prevents a dense brownie-like texture.
• If using smaller eggs, 10-11 may be needed to reach 500 g.
• Store in the fridge for up to 4 days.