In a large bowl, cream butter and confectioners' sugar until light and fluffy. Gradually add 2 cups flour just until combined.
Press mixture into a greased 13x9-in. baking pan. Bake at 350° for 20 minutes or until lightly browned.
Meanwhile, in a large bowl, beat the eggs, sugar, lemon juice and orange zest. Combine the baking powder and remaining flour; gradually add to egg mixture. Sprinkle raspberries over the crust. Pour filling over the berries.
Bake for 30-35 minutes or until lightly browned and filing is set. Cool on a wire rack. Store in the refrigerator.