Beat Eggs & Sugar: Add 4 large eggs and 2 cups granulated white sugar to a stand mixer or large bowl. Beat on medium-high speed for a full 6–7 minutes until the mixture triples in volume, turns pale ivory-white, and falls in thick ribbons off the beater. Do not cut this time short — this step creates the signature crispy top crust.

Add Dry Ingredients: Sift 0.8 cups unsweetened cocoa powder and 0.5 cups all-purpose flour directly into the beaten mixture. Add 1 teaspoons pure vanilla extract. Gently fold with a spatula on the lowest mixer setting until no dry streaks remain. Do not overmix — preserve the air built up in Step 1.

Fold in Melted Butter: Pour in 7.9 ounces unsalted butter, melted and cooled — it must be melted and fully cooled before adding. Gently mix until smooth and glossy. Hot butter will deflate the batter and risk scrambling the eggs.

Set Up the Water Bath: Pour the batter into an 8x8 inch baking dish. Place it inside a larger roasting pan. Carefully pour hot water into the outer pan until it reaches halfway up the sides of the inner dish. This water bath keeps the center soft and pudding-like while the top crust forms.

Bake at 325°F: Place the entire setup into a preheated oven at 325°F (165°C). Bake for 60 minutes

. Do not open the oven door during baking. After 1 hour, the top should look set and slightly crackled. The center will still have a gentle wobble — that's perfect.

Rest & Develop the Crust: Remove from the oven and allow to cool at room temperature for at least 20–30 minutes

. The crispy crackled crust forms as it cools — not in the oven. Do not skip this resting step.

Serve & Enjoy: Scoop warm into bowls directly from the baking dish. Serve with a scoop of vanilla ice cream, freshly whipped cream, or a light dusting of powdered sugar. Best enjoyed warm while the center is still soft and fudgy.