Beat the butter and both sugars until creamy
Add the egg, egg yolk and mix until combined
Add the flour, baking powder and salt and mix to form a thick cookie dough
Fold through most of the milk chocolate, saving some for the tops
Divide into 12 large cookie dough balls and freeze for 60 minutes
Bake at 170°C fan for 12-14 minutes
Straight from the oven, press on the remaining chocolate chunks and pieces of salted wavy crisps
Finish with a sprinkle of flaky sea salt and leave on the tray for 10-15 minutes to set
