Put all the ingredients for the Lemon curd in a small, heavy-based pan and heat gently, stirring constantly with a wooden spoon – don’t let the mixture boil or the eggs will scramble.
When it’s thickened enough to coat the back of the spoon quite thickly, take off the heat and fill a clean 12oz/e340g jar. Seal and leave to cool.
If you want perfection, sieve the curd before bottling to remove any cooked egg whites. But sieving will also remove the lemon zest, which you really want to keep if you want that extra zingyness in the taste.
Use the curd to fill all cakes and even add a few tablespoons to your cake batter mix, along with more lemon zest when making Lemon Drizzle cakes.
A few dollops mixed in with your buttercream and frosting will give that extra kick of flavour.