Preheat the oven to 350 degrees. Line two large baking sheets with parchment paper or silicone baking mats.
In a bowl, whisk together flour, baking soda, and salt. Set aside.
In another bowl beat together butter and peanut butter until light and creamy. Add sugars and beat until well combined. Add eggs, one at a time, beating well after each addition and scraping down the sides as needed. Add milk and vanilla and beat until combined.
Add flour mixture and stir until just combined. Pour in all three chips and beat on slow speed until just combined.
Drop cookies by the rounded Tablespoonful onto the prepared cookie sheets, leaving an inch between them. Press the cookies down with your palm to about a 1/4 in thick.
Bake for 10-12 minutes or until just barely set on the outsides. These cookies don't really brown. Take them out when the edges are set and the centers still look puffy. Press a few extra Reese's pieces into the tops of the cookies, if desired. Let them sit on the hot baking sheet for a few minutes, then transfer to a cooling rack to cool completely. I always err on the side of under baking so they stay nice and soft.