Mystery Bars

2 c. brown sugar

1 t. baking powder

1 c. butter, melted

1 t. vanilla

powdered sugar

1 1/4 c. plain flour

2 eggs

dash salt

1 c. chopped nuts

Mix all ingredients together, except powdered sugar. Pour in square pan. Bake at 350 for 40 minutes. Cut in squares and roll in powdered sugar.