In large bowl combine butter, granulated sugar, and brown sugar. Beat until light and fluffy. Add eggs; beat well. Add milk and vanilla, beating to combine. Slowly add baking mix and cocoa beating on low speed to combine. Stir in all chocolate chips.
Pour into greased 9×13 inch baking pan.
Bake for 33 to 37 minutes or until center is set. Cool completely in pan.