Line a baking sheet with parchment or silicone mat and set aside.
In a small bowl, add your flour, salt, baking soda, and baking powder and whisk together. Set aside.
Chop your pretzels into small bits (or place them in a bag and pound them with a spoon or rolling pin), and if you are using chocolate bar, chop that into small bits as well.
In the bowl of your stand mixer or a large bowl with a hand mixer, add your butter and sugar and cream them together (about 3 minutes).
Add in your vanilla, egg, and egg yolk and mix well until the egg is incorporated into the dough. If you are using a stand mixer, make sure to scrape the bottom so all dough is beaten into the egg.
Add your dry ingredients to the wet, and mix on low until the dough just comes together.
Add in your pretzels, peppermint bits, and white chocolate and use a rubber spatula or wooden spoon to stir them into the cookie dough, making sure they are all dispersed evenly.
Scoop your dough into cookie portions onto your prepared cookie sheet. They can be close together as the dough needs to be chilled first and you will move them before baking. Cover your pan well (I don't recommend foil, but plastic wrap or foil over plastic wrap if you don't have a cookie sheet cover) and chill in the fridge for about 8 hours - overnight is easiest.
After your dough has chilled, preheat your oven to 350°F. Leave your cookie dough in the fridge while the oven preheats.
Line another cookie sheet with parchment and remove some of your cookie portions to the new sheet. Place in the oven on the middle rack and bake for 13-16 minutes. The cookies will be done but softer and a little doughier at 12-13 minutes with lightly golden edges. At 16 minutes the cookie will be golden all over and crispy exterior with chewy inside. Either is fine, just personal preference.
Remove your cookies from the baking sheet to a wire rack to finish cooling. Store in an airtight container for up to 4-5 days. Enjoy!
