Coat a 10-in. fluted tube pan with cooking spray and dust with flour; set aside. In a large bowl, beat butter and brown sugar until crumbly, about 2 minutes. Add eggs and egg whites, one at a time, beating well after each addition. Beat in the yogurt, oil and lemon juice. Combine the flour, lemon zest, poppy seeds, baking powder, baking soda and salt; add to the creamed mixture alternately with milk. Pour into prepared pan.
Bake at 350° for 50-55 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before inverting onto a wire rack. Cool 10 minutes longer. Place rack on waxed paper. For glaze, combine confectioners' sugar and lemon juice; brush over warm cake. Sprinkle with poppy seeds. Cool completely before cutting.