Preheat oven to 350°F. Brush an 8x8-inch square baking pan with melted butter and line the pan with parchment paper, leaving a 2-inch overhang on two sides.

In a large bowl, whisk butter and sugars until smooth. Whisk in egg and vanilla until fully incorporated.

Add flour and salt and mix just until moistened (do not over mix). Fold in ½ cup semi-sweet chocolate chips.

Transfer batter to prepared pan and smooth top with a rubber spatula. Sprinkle the top with the remaining chocolate chips.

Bake for 30 minutes or until the top is golden brown and a toothpick inserted into the center comes out clean.

Set the pan on a wire rack and let cool completely. Using the parchment overhang, lift the blondies from the pan and transfer them to a cutting board. Cut into squares.