In a large bowl, cream the butter, sugar and lemon zest together with a spatula. Add the eggs one at a time, mixing after each.
Mix together the dry ingredients, then add a third of it to the wet mixture (do not over mix or your muffins will not rise).
Add half the yogurt and stir until combined, then another third of the flour, mix. Then add the rest of the yogurt and the rest of the flour. Stir in the poppy seeds.
Pour into a greased/paper lined muffin tin, and sprinkle the tops with sugar.Bake at 375°F for 25-30 minutes, or until internal temperature of muffin reaches 205°F, using an instant read thermometer.