1. Preheat oven to 350F.
2. Combine poppy seeds and milk, lets stand 30 minutes. Cream butter and sugar in a mixer until light and creamy. Ass yolks one at a time, beating well after each addition. Stir in flour, baking powder, salt, poppy seed mixture, and vanilla. Beat egg whites until almost stiff. Fold into batter. Spoon batter into a greased and floured 9-inch Bundt or Kugglehopf pan or spring form pan. Bake 45-50 minutes. Cool 15 minutes, then remove from pan. 16 servings.