Step 1

Preheat the oven to 375 F.

Step 2

In the bowl of a stand mixer or with a handheld mixer, beat butter and sugars to combine.

Step 3

Beat in egg and vanilla until smooth.

Step 4

Add flour, salt, baking powder, and baking soda; beat just to combine.

Step 5

Add 1 ½ cups chocolate chunks and beat lightly, just to distribute throughout the dough.

Step 6

Press evenly into a 6- or 8-inch cast iron skillet.

Step 7

Sprinkle remaining chocolate evenly over the top.

Step 8

Bake for 24 to 26 minutes, until golden brown along the edges but still gooey in the center.

Step 9

Serve warm, topped with ice cream as desired.