Method
Remove the zest from the lemon and place with the butter and caster sugar in a wide-mouthed glass preserving jar with the rubber sealing gasket removed.

Place the whole lemon into the roasting oven for 2-3 minutes to warm it so it will yield the most juice. Remove and cut in half and squeeze out the juice and pour into the jar and close the lid loosely.

Place the preserving jar in the simmering oven for 30 minutes to warm through and melt the butter and allow the sugar to dissolve in the lemon juice.

Remove from the oven and stir the contents until they are mixed and smooth. Add the yolks and whole egg to the hot mixture immediately whisk with a rotary whisk for about a minute, until the eggs are thoroughly distributed.

Replace the lid and return the jar to the simmering oven for 1¼ - 1¾ hours. Remove from the oven and give the mixture a final stir with a spoon then leave to cool for an hour. Replace the rubber sealing gasket on the lid before sealing the jar. Store in the refrigerator where it will keep for up to three weeks.

Hints & Tips
Use a dry pastry brush to easily remove all of the zest from a microplane or fine grater when adding this to the jar.

Place the preserving jar on a damp cloth so it stays firm while you are whisking the mixture. The rotary whisk may be safely washed in a dishwasher, as can the jar when it is finished, so no washing up by hand with this handy recipe.

Le Parfait glass preserving jars for making lemon curd are available from your nearest Aga Shop – ring to check availability. Alternatively, shop online at www.divertimenti.co.uk . Enter ‘jar’ in the site’s search engine and choose the 50cl size (product code 30018) – this is the size seen in the video.

The three left-over egg whites can be used up to make meringue nests, shells or swirls, using 175g (6oz) caster sugar – this makes just the right amount to fill an Aga cold plain shelf, or make one large Pavlova, following your favourite recipe.