Preheat oven to 350°F (175°C).

In a large bowl, whisk together melted butter, brown sugar, and granulated sugar until smooth and glossy.

Add egg yolks and vanilla. Mix until fully combined.

Stir in flour, cocoa powder, baking soda, and salt until just combined.

Fold in chocolate chips and chocolate chunks.

Press dough evenly into a lightly greased 6-inch skillet. Smooth the top.

Bake for 28–35 minutes, until: Edges are set, Top looks mostly set, Center is still slightly soft but not liquid

Let cool in the skillet for 10–15 minutes before serving. It will continue to set as it rests.