Heat oven to 350°F and line a 9-by-13-inch metal pan with parchment.

Whisk melted butter and both sugars, then whisk in the egg, yolk and vanilla.

Fold in flour, baking soda and salt just until no dry streaks remain.

Reserve 2 tablespoons chips, fold in the rest and press dough evenly into the pan.

Scatter reserved chips over the surface and bake for 22 to 25 minutes until the edges are golden but the center remains soft.

Cool completely in the pan before cutting into 24 rectangles.