Toffee-Topped Bars

2 C firmly packed brown sugar
2 C all-purpose flour
1/2 C butter or margarine, softened
1 tsp baking powder
1/2 tsp salt
1 tsp vanilla extract
1 C milk
1 egg
1 C semi-sweet chocolate chips
1/2 C chopped walnuts
1/4 C unsweetened flaked coconut

Preheat oven to 350. Lightly grease a 13x9" pan. In large mixing bowl, mix together brown sugar and flour. Cut in butter until mixture resembles coarse crumbs. Remove 1 cup of mixture and set aside. To mixture in large bowl, add baking powder and salt. 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 chocolate chips and walnuts. Fold in the coconut. Sprinkle reserved crumb mixture over top of batter in pan. Sprinkle with chocolate chip mixture. Spread topping evenly over the top of the batter. Bake 35 minutes, or until toothpick inserted in center comes out clean. Transfer pan to wire rack; cool completely before slicing.