Ingredients:

  • 1 cup (225g) unsalted butter, melted and slightly cooled
  • 3/4 cup (150g) white granulated sugar
  • 3/4 cup (165g) packed dark brown sugar
  • 1 large egg (50g)
  • 1 large egg yolk (18g)
  • 2 tsp (10ml) pure vanilla extract
  • 2 1/4 cups (280g) all-purpose flour
  • 1 tsp (5g) baking soda
  • 1/2 tsp (3g) salt
  • 2 cups (340g) semi-sweet chocolate chips
  • 1/2 cup (115g) unsalted butter, softened
  • 2 cups (240g) powdered sugar
  • 1/3 cup (35g) cocoa powder
  • 2 tbsp (30ml) heavy cream
  • 1 tsp (5ml) vanilla extract

Instructions:

  1. Preheat the oven to 350°F (175°C). Grease a 9-inch or 10-inch round cake pan with butter and line the bottom with parchment paper.
  2. In a large bowl, whisk together the melted butter, white granulated sugar, and dark brown sugar until the mixture is smooth.
  3. Whisk in the egg, egg yolk, and vanilla extract until the mixture becomes glossy and cohesive.
  4. Using a spatula, fold in the all-purpose flour, baking soda, and salt. Mix only until the flour streaks disappear to avoid over-mixing.
  5. Stir in the semi-sweet chocolate chips, using a mix of whole and slightly crushed chips.
  6. Transfer the dough to the prepared pan and press it evenly across the bottom.
  7. Bake for 25 minutes or until the edges are golden and the center is set but still slightly soft.
  8. If making the optional buttercream, beat softened butter, powdered sugar, cocoa powder, heavy cream, and vanilla until smooth, then frost the cooled cake.