• Preheat your oven to 350℉ (or 180℃).

  Line a 9x13x2 baking pan with parchment paper and spray with a nonstick baking spray.

MAKE THE PRETZEL LAYER:

• In a food processor, measure and add the pretzels. Process until finely crushed. Transfer the pretzel crumbs to a bowl, and pour in the melted butter. Stir to combine. Press the crumbs evenly into the bottom of the pan and bake on the middle rack for 6 minutes. Remove and let cool.

  NOTE: Alternatively, you can add them to a re-sealable bag and bash them up with a rolling pin or the flat side of a meat tenderizer.

MAKE THE COOKIE LAYER:

• In a medium mixing bowl, measure and add flour, baking soda and fine salt. Whisk to combine.
• In the bowl of your stand mixer, fitted with a paddle attachment, measure and add softened butter and both sugars. Then blend until smooth and creamy. Next, add in eggs, egg yolk and the vanilla extract. Then mix on medium just until it comes together.
• Working in batches, add in half of the dry ingredients. Mix until just incorporated, scraping down the sides and bottom of the bowl. Then repeat, adding in the remaining dry ingredients and mixing until just combined. Lastly, add in the milk chocolate chips, mix on low for a few seconds.
• Drop the batter in large spoonfuls on to the pretzel layer. With lightly damp fingers, press to spread the batter, until the entire pan is covered. Slide the pan into your preheated oven and bake it off for 20-24 minutes or until the top is golden and a tester comes out clean.
• Remove and let cool for 30 minutes before using the parchment paper to lift and transfer to a wire rack to finish cooling. Once mostly cool, I like to pop them into the fridge for 1 hour. Remove cut into 12 to 15 squares and serve.

  NOTE: Don’t be alarmed if some of the pretzel layer doesn’t stick completely. This is normal.