Preheat your oven to 350°F (175°C). Spread the all-purpose flour evenly on a baking sheet and bake for 5 minutes to heat-treat the flour. Let it cool completely before using.
In a large mixing bowl, combine the softened unsalted butter, creamy peanut butter, brown sugar, and granulated sugar. Beat with an electric mixer on medium speed until the mixture is smooth and creamy, about 2 minutes.
Add the vanilla extract and salt to the butter and peanut butter mixture. Mix until fully incorporated.
Gradually add the heat-treated flour to the wet ingredients, mixing on low speed until just combined.
Add the milk and continue mixing until the dough reaches a soft, scoopable consistency. If the dough is too dry, add a little more milk, one teaspoon at a time.
Fold in the mini semisweet chocolate chips evenly throughout the dough.
Serve immediately or refrigerate in an airtight container for up to 5 days. Enjoy as a snack or use as a topping for ice cream or desserts.