Preheat oven to 350*F. Lightly grease a 13 x 9 inch baking pan; set aside.
In a large mixing bowl, mix together the brown sugar and flour.
Using a pastry cutter or two knives, cut in the butter until mixture resembles coarse crumbs. Remove 1 cup of mixture and set aside.
To mixture in large bowl, add baking powder and salt. Using a fork, lightly beat in vanilla, milk and egg.
Continue beating until a smooth batter forms. Pour batter into prepared baking pan.
In a small bowl, combine the chocolate chips and walnuts. Fold in the coconut.
sprinkle reserved crumb mixture over top of batter in pan. Sprinkle with the chocolate chips and walnuts.
Using a long flat spatula, spread topping evenly over the top of the batter in pan.
Bake bars for 35 minutes, or until a skewer inserted in center comes out clean.
Transfer pan to a wire rack. Cool bars in pan completely before slicing.
Using a serrated knife, cut into 24 bars. Store in airtight container for up to 5 days.