Coat a 9-inch (3 inches deep) springform pan with cooking spray; dust with 2 tablespoons sugar. Place butter in a large bowl; beat with a mixer at medium speed until creamy and pale (about 2 minutes); gradually add 1 1/3 cups sugar. Beat at high speed 3 minutes or until fluffy. Beat in vanilla. Add egg whites, 1 at a time, beating well after each addition. Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking soda, and salt, stirring with a whisk. Combine milk and buttermilk. Add flour mixture and buttermilk mixture alternately to sugar mixture, beginning and ending with flour mixture. Fold in coconut.
Bake at 350° for 55 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 15 minutes on wire rack; remove from pan. Cool completely on wire rack. Sprinkle with powdered sugar. Serve with Ginger Ice Milk.