Preheat the oven to 175 °C.
Cream butter with sugar and gradually add eggs. Stir in the lemon zest. Finally, mix in the flour.
Pour the batter into a springform pan (26 cm diameter) and smooth it out. Bake in a hot oven for about 1 hour until golden brown. (Do a wooden stick test).
Remove the pan from the oven and immediately loosen the cake from the edge. Let cool well on a cooling rack.
In the meantime, prepare the glaze by mixing confectioners’ sugar, water and lemon oil. Fold in the lemon zest.
Spread the glaze on the cooled cake, sprinkle with the toasted almond flakes and leave to dry.