Preheat oven to 180°C / 356°F. Line muffin tin with paper molds.
In a bowl, combine dry ingredients: flour, baking powder and pinch of salt.
Wash and dry lemon. Grate skin into a fine zest, then half the lemon and squeeze out the juice, removing any seeds.
Divide eggs into yolks and egg whites. Whisk egg whites until they turn into a firm snow. Whisk yolks with 1/2 cup sugar, then add greek yogurt, vanilla essence and grated lemon zest.
Add the yolk mixture to the flour mix and add 1/3 of the egg whites. Combine gently, then add poppy seeds and fold in the remaining egg whites.
Pour mixture into the muffin molds, then put into the oven to bake for about 18 minutes, or until golden brown. When baked, remove from oven and set aside to cool.
Mix together 1 cup confectioners' sugar with about 3 tbs of lemon juice or more, if needed. Drizzle the sugar icing on top of the muffins and let it set, then serve.