Pre-heat the oven to 325° F.
Grease the loaf pan(s) and line with parchment paper; set aside.
Place the eggs and granulated sugar in the bowl of an electric mixer, with the whisk attachment in place, and whisk on medium-high speed for about 2 minutes, until pale and frothy.
Add the sour cream and continue to beat, for about 2 minutes, until the mixture has combined.
In the meantime, melt the butter in a small saucepan over low heat; stir in the poppy seeds and lemon zest; set aside.
Sift the flour, baking powder and salt together into a bowl; then use a rubber spatula to fold this into the egg mixture before folding in the butter, poppy seeds and zest.
Spoon the mixture into the loaf pan(s) so that it rises three-quarters of the way up the sides.
Place on a baking sheet, place in the pre-heated oven and bake for 55 to 65 minutes, or until a skewer inserted into the center comes out clean.
Do not open the oven door to check the cake during the first 45 minutes of baking.
While the cake is baking, in a small bowl, whisk the confectioners' sugar with the lemon juice to make the glaze; set aside.
Pour the glaze over the top of the cake as soon as it comes out of the oven, spreading it over the top so that it sinks in and creates a nice coating; set aside to cool for 30 minutes before removing from the pan.
Allow the cake to come to room temperature before serving.
