Preheat your oven to 375°F (190°C).
In a mixing bowl, cream together the peanut butter, softened butter, white sugar, and brown sugar using a hand mixer until well blended. Beat in the egg, milk, and vanilla extract for about 2-3 minutes until everything is smooth and creamy.
In another bowl, combine the flour, baking powder, and salt thoroughly.
Carefully add the dry mixture to the wet ingredients in batches, mixing just until combined.
Stir in the semi-sweet chocolate chips until they are evenly distributed throughout the dough.
Scoop tablespoonfuls of dough and roll them into balls before placing them about two inches apart on ungreased baking sheets or parchment-lined sheets.
Bake your cookies in the preheated oven for about 8-10 minutes. Allow cooling on baking sheets briefly before transferring them to wire racks to cool completely.