Preheat oven to 375 F.
In medium mixing bowl sift together flour, baking soda, and salt. In a large mixing bowl, cream peanut butter, butter, and brown sugar. Add egg and stir to combine. Add milk and vanilla and mix until thoroughly combined. Add dry ingredients to peanut butter mixture. Stir in chocolate chips. Drop by large spoonful onto cookie sheet and flatten with bottom of a glass dipped in flour. Bake for 7-8 minutes in preheated oven until edges turn golden. Let cool on pan 3 minutes then transfer to wire rack to cool. Makes 2 dozen cookies.