Preheat the oven to 350°F. Grease a 9 x 5 inch loaf pan and line it with a strip of parchment paper. Put the butter, sugar, lemon zest, and lemon extract (if using) in a large bowl, and using an electric mixer, beat for 5 minutes or until light and fluffy.
Put the eggs in a pitcher and beat them together, then, working slowly, add the egg to the butter mixture, a little at a time, beating until fully combined before adding more. Once all the egg has been combined, sift in half the flour, mixing until just combined. Add the sour cream and mix until fully combined, then sift in the remaining flour and mix until just combined—don’t over-mix, as it can make the cake tough.
Scrape the mixture into the prepared pan and gently level the top. Bake for 55 to 60 minutes until golden brown and a skewer inserted into the center of the cake comes out clean. Let cool in the pan for 10 minutes before inverting it onto a wire rack to cool until lukewarm.
To make the glaze, mix the lemon juice and powdered sugar together in a bowl to make a thin, pourable glaze. Put a piece of parchment paper under the wire rack to catch the drips from the glaze. Pour the lemon glaze over the lukewarm cake, and use a pastry brush to spread it over the entire surface in an even layer. Leave the cake to cool completely on the wire rack before serving.
This cake will keep for 3 to 4 days stored in an airtight container; it can also be frozen for up to one month without the glaze.
Excerpted from Patisserie Made Simple by Edd Kimber. Published by Kyle Books. Photography by Laura Edwards.