In a stand mixer, combine butter, milk and sugars until light and fluffy. Add egg and vanilla, mix until combined. Slowly add dry ingredients until combined. Then add chocolate chips. Fold in blueberries with a silicone spoon.
Use an ice cream scoop to create 2" scoops of cookie dough onto parchment lined baking sheet. Bake for 14-18 minutes, until edges are golden brown. Makes 12 large cookies.