Equipment
* optional
Ingredients
Wet Ingredients
- 115 g unsalted butter, cut into pieces
- 150 g light brown sugar, packed
- 50 g granulated sugar
- 10 ml vanilla extract
- 1 egg, room temperature
Dry Ingredients
- 160 g all-purpose flour
- 3 g baking soda
- 3 g kosher salt
Mix-ins
- 150 g semisweet chocolate chips
- 50 g walnuts, chopped and lightly toasted
Nutrition (per serving)
Method
Preheat the oven to 175°C (350°F). Gather and weigh all ingredients.
Place the cast-iron skillet over medium-low heat on the stove. Add the unsalted butter and stir gently until completely melted. Remove the skillet from the heat and let it cool for 5 minutes.
Add the light brown sugar and granulated sugar directly into the skillet with the warm melted butter. Mix vigorously with a silicone spatula until thoroughly combined and smooth.
Whisk the vanilla extract and the egg into the sugar mixture until the batter becomes glossy and slightly lighter in color.
Sprinkle the all-purpose flour, baking soda, and kosher salt evenly over the wet ingredients in the skillet. Gently fold the dry ingredients in until just a few flour streaks remain.
Fold in the semisweet chocolate chips and chopped walnuts, reserving a small handful of chocolate chips to gently press into the top surface of the dough. Smooth the dough into an even, flat layer across the bottom of the skillet.
Bake in the preheated oven for 18 to 22 minutes. The edges should be golden brown and the center should reach a safe internal temperature of 74°C (165°F) for the egg, though it will still look soft and underbaked to maintain the gooey texture.
Remove the skillet from the oven and allow it to rest for 10 minutes. The residual heat from the cast iron will continue to gently bake the center.
Chef's Notes
- Carryover cooking is significant when using cast iron. The heavy metal retains heat incredibly well, meaning the cookie continues to bake for up to 10 minutes after leaving the oven. Pulling it early is the secret to a molten center.
- Using a mix of brown and white sugar is crucial for the perfect texture. Brown sugar provides chewiness, moisture, and a deep molasses note, while white sugar ensures the edges crisp up beautifully.
- Always reserve a small handful of chocolate chips to press into the top right before baking. This creates an appealing, bakery-style finish with distinct, glossy puddles of chocolate on the surface.
Storage
Refrigerator: 3 days — Wrap tightly in foil or transfer to an airtight container.
Freezer: 1 month — Freeze baked individual slices tightly wrapped.
Reheating: Warm in a 150C/300F oven for 5 to 10 minutes until gooey, or microwave individual slices for 15 seconds.
