Brown butter in a saucepan over medium heat until golden and nutty.

Remove from heat, pour in a large mixing bowl and stir in milk powder. Let the butter cool for 10-15 minutes.

When the butter has cooled, whisk in sugars till fully combined and glossy. It will look a little grainy.

Add in the egg, egg yolk and vanilla extract. Whisk till combined and smooth.

Whisk dry ingredients in a separate bowl till combined, flours, cornstarch, salt, baking powder and baking soda.

Fold dry into wet just until almost combined, leave a few noticeable flour streaks.

Stir in chopped cookies and mix gently just enough till combined and you don't see any more flour.

Cover and chill dough 30 to 60 minutes.

Preheat oven to 350°F. Line a cookie sheet with parchment paper and with a cookie or ice cream scoop to portion out the dough into equal size balls. Space out dough at least 2 inches apart. Optional to press extra cookies pieces to the top of the cookie dough for appearance.

Bake at 350°F for 10-11 minutes or until edges are light golden brown, and the middle of the cookie is soft and puffed.

Cool the baked cookies for 5 minutes on the sheet pan, then transfer to rack to fully cool. The centers will appear underbaked at first and will continue to cook through even on the cooling rack.