Preheat the oven to 180°C (350°F) and line a 2lb loaf tin with parchment paper.
In a large mixing bowl, cream the softened butter and granulated sugar together until the mixture is pale and fluffy.
Add the eggs one at a time, beating well after each addition and adding a spoonful of flour if the mixture begins to curdle.
Sift the remaining flour and baking powder into the bowl, then gently fold into the batter using a spatula.
Fold in the lemon zest and poppy seeds until evenly distributed.
Pour the batter into the prepared loaf tin and smooth the surface with the back of a spoon.
Bake for 45 to 50 minutes until the cake is golden brown and a skewer inserted into the center comes out clean.
Allow the cake to cool completely on a wire rack before glazing.
Whisk the powdered sugar and lemon juice together until smooth, then drizzle over the top of the cooled cake.
Decorate the top of the glaze with chocolate mini eggs before the icing sets.