1. Heat oven to 325 degrees F. Grease and flour 12-cup (10-inch) tube or Bundt pan.
2. Combine flour, baking powder, baking soda and salt in bowl.
3. Beat together butter and 3/4 cup of the sugar in large bowl until light and fluffy. Beat in the 3 eggs, one at a time.
4. Add flour mixture alternately with buttermilk to egg mixture, starting and ending with dry ingredients and beating well after each addition; beat until smooth. Beat in poppy seeds and lemon rind.
5. Beat remaining 4 egg whites in large bowl until foamy. Gradually beat in remaining 1/4 cup sugar until soft peaks form. Fold into batter until no white remains. Scrape into the prepared pan.
6. Bake in 325 degree F oven 45 to 50 minutes or until top springs back when lightly touched with finger. Let stand 15 minutes. Loosen cake around tube and sides with spatula; invert onto rack to cool completely. Spoon or drizzle Lemon Glaze over top of cake, letting it drip down sides. Sprinkle with lemon rind if desired.
1. Whisk together confectioners sugar, milk, lemon rind, fresh lemon juice and salt in bowl until well blended and smooth. To thin glaze for the drizzle, stir in milk, drop by drop, until drizzling consistency.