Heat-treat the flour by spreading it evenly on a baking sheet and baking at 350°F (175°C) for 5 minutes to kill any bacteria. Let it cool completely before using.
In a large mixing bowl, beat the softened unsalted butter, creamy peanut butter, light brown sugar, and granulated sugar together until creamy and smooth, about 2-3 minutes.
Add the vanilla extract and salt to the peanut butter mixture and mix until combined.
Gradually add the heat-treated flour to the wet ingredients, mixing on low speed until fully incorporated.
Add the milk and continue mixing until the dough reaches a soft, scoopable consistency.
Fold in the mini semisweet chocolate chips evenly throughout the dough.
Serve immediately or refrigerate in an airtight container for up to 5 days.