Unlike many poppy seed cakes, this one is baked in layers and generous with the seeds--about 1/4 cup per layer. The lemon buttercream filling is perfect with the nutty tasting cake.
Combine poppy seeds and 1 cup milk in small saucepan. Heat to boiling. Remove from heat; cover; let stand 1 hour.
Heat oven to 350 degrees F. Grease and flour three 9 x 2-inch round layer-cake pans.
Sift together cake flour, baking powder and salt into a bowl.
Beat egg whites in large bowl on high speed until foamy. Beat in 1 cup sugar, 1 tablespoon at a time, until soft peaks form.
Beat together butter and remaining 1-1/2 cups sugar in large bowl on medium speed until smooth and creamy, about 3 minutes. Blend in poppy seed mixture and lemon rind.
On low speed, beat in flour mixture alternately with remaining 1-1/4 cups milk until smooth.
Fold in egg whites until no streaks of white remain. Divide batter among prepared pans.
Bake in 350 degree F oven for 30 to 35 minutes or until centers spring back and wooden pick inserted in centers comes out clean. Using thin metal spatula, gently loosen sides of cakes. Cool layers in pans on wire racks 10 minutes. Invert layers onto wire racks to cool completely.
Beat butter on high speed in large bowl until fluffy. On low speed, beat in confectioners sugar alternately with lemon juice until smooth and creamy. Stir in lemon rind and salt.
. Rub your hand around the edge of the cake layers to loosen and rub off any crumbs. For neater fit, trim the rounded tops of the layers with serrated knife. Frost with Lemon Butter Cream Frosting.