Oven 350 Deg F (180C) Prep a baking sheet with parchment paper.
Melt butter and peanut butter together (stovetop in a saucepan or microwave in a large glass bowl) Let cool slightly, 2-3 min.
100 g unsalted butter, 60 g peanut butter
In another bowl whisk together the flour, salt and baking soda. ( You could wait and just add these directly into the pan or bowl later - I personally like to whisk together first)
145 g AP flour, ½ teaspoon baking soda, ⅛ teaspoon kosher salt
Whisk the brown sugar, confectioners sugar, egg yolks and vanilla into the melted butter mixture until well combined.
120 g brown sugar, 40 g confectioners sugar, 2 large egg yolks, ½ teaspoon vanilla extract
Pour the flour mixture into the butter mixture and stir until combined and no flour streaks remain. Add in the peanut butter and chocolate chips and mix quickly.
55 g each chopped chocolate and peanut butter chips
Divide into 4 balls (about 160 g each) and place a few inches apart on the baking sheet. Press the dough balls down just slightly and sprinkle a little flake salt on top as well as a few more peanut butter and chocolate chips.
Flake salt for the tops
Bake 12-15 minutes. Let cool a few minutes before eating.