Preheat oven to 350 degrees F (175 degrees C). Line 12 muffin cups with paper liners.
Beat sugar and butter with an electric mixer in a large bowl until light and fluffy. The mixture should be noticeably lighter in color.
Add egg yolks one at a time, allowing the first to blend into the butter mixture before adding the last. Beat almond extract and lemon zest into the mixture.
Stir flour, baking powder, baking soda, and salt together in a separate bowl; add to creamed mixture alternately with buttermilk, mixing until just combined into a batter. Fold poppy seeds through the batter.
Beat egg whites in a glass or metal bowl until stiff peaks form. Lift your beater or whisk straight up: the egg whites will form sharp peaks; fold into the batter. Spoon batter into prepared muffin cups to about 2/3 full.
Bake in the preheated oven until golden and the tops spring back when lightly pressed, 15 to 18 minutes; remove from pan and let cool on rack.
