Butter and flour-dust a 10-inch decorative tube pan.
In a small bowl, mix poppy seed, buttermilk, and almond extract.
In a deep bowl, beat egg whites with a mixer on high until foamy. Continue beating and gradually add 1/4 cup sugar. Beat until whites hold stiff, shiny peaks.
In another bowl, using unwashed beaters, beat 1 cup butter and 1 1/2 cups sugar on high speed until light and fluffy.
Add egg yolks and beat until well blended. Stir in poppy seed mixture.