In a medium bowl, add the flour, baking soda, baking powder, and salt. Set aside.
Add both sugars to a mixing bowl, then add cooled browned butter. Mixing until combined.
Add egg & vanilla, mixing until light.
Add the dry ingredients and mix (or fold by hand) until the flour is almost incorporated. You still want to see some spots.
Add the white chocolate and skor/toffee pieces and fold until combined.
Scoop the cookies onto a parchment lined tray, cover with cling wrap and place in the fridge for 1 hour.
Preheat oven to 350, then bake cookies for 12 minutes.
Remove from the oven and bang the pan on a bench 3-5 times, then let cool on the tray for 5 minutes before transferring to a cooling rack (or eating).