In a medium bowl sift together flour, baking soda and salt. Set aside.

Place the melted butter in a large bowl and whisk in granulated sugar, brown sugar and pudding mix. Whisk in the egg and vanilla extract. Add flour mixture and mix just until combined. Do not over mix. Stir in butterscotch chips and pretzels.

Chill the dough for 30 minutes (or up to 3 days). This step is not mandatory since the cookies will be thick enough even without refrigerating.

Preheat oven to 175C/350F degrees. Line pans with parchment paper.

If the cookie dough is hard to handle, leave it on the counter for a few minutes.

Drop rounded balls of dough onto prepared baking sheet, the size of 3 tablespoons each. Bake for 9-11 minutes, until cookies just begin to brown at the edges. Cookies will appear undone but will continue to bake on the warm baking sheet. Leave to cool for 10 minutes, then transfer to a wire rack to cool completely.