Place the butter in a heavy bottom, medium saucepan and melt over low heat. When the butter has melted, increase the heat to medium and cook until the solids in the butter turn golden brown and it develops a nutty fragrance (watch the butter closely as it can burn and be ruined very quickly). Remove from heat, set aside and cool for 20 minutes.
In a medium mixing bowl, sift together the flour, salt, and baking soda and set aside.
Fit stand mixer with a paddle attachment. Pour cooled butter into the stand mixer bowl and add both sugars. Beat on medium for 3 minutes. Add the egg, egg yolk and beat just to combine. Add the cream and vanilla and beat on medium for another 3 minutes. Slowly add the flour mixture beating on low speed after each addition. When all the flour mixture is added, beat on medium until well incorporated. Using a sturdy spoon add the pretzels and both chips and stir until they are evenly distributed.
Cover and refrigerate for at least 8 hours (It will be worth it, I promise).
Preheat oven to 350 degrees. Line baking sheets with Silpats or parchment.
Remove chilled dough from the fridge. Scoop out the dough with a tablespoon and roll into a ball. (a little smaller than the size of a golf ball). The dough will be almost brittle-just kinda chip at it and gather the pieces together forming a ball. The heat from your hands will make the brittle dough nicely pliable. Place balls on the prepared baking sheets and flatten slightly.
Bake for 10-12 minutes or until they're baked through the center. Mine cooked 11 minutes and were slightly underbaked, which is how I like em! Allow the cookie to rest on the baking sheet for about 10 minutes then transfer them to a cooling rack.