Preheat the oven to 180°C (350°F) and lightly grease 2 x 12-hole madeleine tins with cooking spray, including the ridges between each shell.
In a large bowl, add the flour, baking powder, sugar, eggs, honey, melted butter, vanilla, lemon zest and poppy seeds. Whisk until you have a smooth batter.
Spoon about a dessertspoon of batter into each mould, filling to just level with the top of the shell.
Bake for 8 to 10 minutes until golden brown and firm to the touch.
While the madeleines bake, whisk together the icing sugar and lemon juice until you have a thick but slightly runny glaze.
Allow the madeleines to cool for a few minutes in the tin, then remove and cool slightly on a rack. Dip the underside of each madeleine into the glaze, turn it over and allow the excess to drip off. The glaze will harden as it sets.