In a saucepan, bring the apricots and water to a boil. Reduce heat; simmer, uncovered, for 10 minutes. Drain and cool. Chop apricots and set aside.
In a bowl, combine 2-1/2 cups biscuit mix and sugar. Cut in butter until crumbly. Pat into an ungreased 15x10x1-in. baking pan. Bake at 350° for 10-12 minutes or until edges are lightly browned. Cool on a wire rack.
In a large bowl, beat brown sugar and eggs until blended. Stir in the apricots, walnuts, vanilla and remaining biscuit mix; spread over crust.
Bake for 20-25 minutes or until golden brown. Cool on a wire rack. Cut into bars. Dust with confectioners' sugar. Store in the refrigerator.