Cream butter until soft. Blend in flour, sugar and salt. Spread mixture in even layer in ungreased jelly roll pan (15x10x1) If mixture is too dry to spread, add 1-2 more tbsp butter. Bake in 350F degree oven for 10 minutes (approx--top will not be brown, but edges can be slightly brown. While cookie layer bakes, beat eggs until light and fluffy. Stir in brown sugar, firmly packed. Add flour, baking powder, and vanilla. Beat until thick and smooth. Fold in angel flake coconut and chopped pecans (or walnuts). Remove cookie crust from oven. Spread mixture over cookie crust. Bake 20 minutes at 350F, or until golden brown and firm on top. When cool, sift powdered sugar liberally over top, then cut into squares and enjoy!