Preheat oven to 350 degrees.  Grease a muffin pan. 

Cream the butter and sugar, beat in the eggs.  Stir in the lemon zest and poppy seeds.  In a separate bowl, stir together the flour, baking powder and salt.  Gently stir the flour mixture into the butter mixture, alternately with the milk.  Do not over stir.

Fill the muffin tins almost to the top with batter.  Bake 15 minutes for mini-muffins and 20 minutes for regular size.  Cool slightly, then remove muffins.