Combine butter, sugar, flour, cocoa, baking powder, eggs, milk, and 1 1/2 teaspoon of vanilla; beat well. Stir in nuts. Spread into a greased and floured 13 x 9 inch pan. Bake 40 minutes.
Just before brownies are done, melt chips in a saucepan with 1 1/2 teaspoon vanilla and condensed milk. Spread fudge mixture over hot brownies. Cool. Chill and cut into bars.