Preheat your oven to 350 degrees
In a large bowl, combine 8 tablespoons of room temperature butter with 1/3 cup of creamy peanut butter, 2/3 cup of granulated sugar, 1/3 cup of brown sugar, 1 large egg, 1 teaspoon of vanilla extract and 1/4 cup of whole milkĀ
Using an electric hand mixer or stiff whisk, beat until smooth and fully combined
Add 2 cups of all purpose flour, 1/4 cup of unsweetened cocoa powder, 1/2 teaspoon of baking soda and 1/4 teaspoon of salt and mix until the dry ingredients are just combined
Gently fold in 1 cup of roughly chopped peanut butter cups and 2/3 cup of milk chocolate chips
Drop 2 tablespoons of dough about 3 inches apart onto a non-stick or parchment lined baking sheet and press the dough out into a bit of a disk (this dough won't spread much as it bakes, so pressing the dough out will give it a head start)
Bake in a 350 degree oven for 12-14 minutes or until the edges of the cookies feel lightly set
Transfer the baking sheet onto a cooling rack or cutting board and sprinkle lightly with flaky sea salt or fleur de sel
Allow the cookies to cool for 10 minutes before transferring onto a cooling rack to cool fully
Enjoy with cold milk
Store leftovers at room temperature in an airtight container