Preheat oven to 180C. Place melted butter, vanilla and sugars in bow of electric mixer and beat for 1-2 minutes until pale and creamy. Add egg and extra egg yolk and beat to combine. Stir in flour, baking powder and salt. Add chocolate, pretzels and potato crisps and mix well.

Spoon heaped tablespoons of mixture onto lined baking trays, leaving about 5cm in between each to allow the mixture to spread. Flatten slightly. Bake for 8 to 10 minutes until edges are golden. Cool on trays before transferring to an airtight container. Cookies will last for up to 1 week.