- Finely grated zest 2 lemons and juice 4 large lemons, plus 1 whole lemon
- 425g caster sugar
- 3 large free-range eggs, plus 3 whites
- 35g unsalted butter, cubed
- 2 gelatine leaves, soaked in cold water (we used Costa)
- 200ml double cream
- 8 ginger biscuits, broken into pieces
- First, make a lemon curd. Put the lemon zest and juice of 2 lemons in a heatproof glass bowl set over a pan of simmering water (don’t let the water touch the bowl) and warm for 3-4 minutes. Stir in 125g of the sugar and gently heat until dissolved. Strain into a heatproof jug.
- Whisk 3 whole eggs into the juice, then pour the mix back into the bowl and set over the simmering water. Stir with a spatula for 10-12 minutes in a figure-of-eight motion, scraping the bottom of the bowl so it doesn’t stick and curdle. As it starts to thicken, turn the heat down slightly. It’s ready when the curd drops off the spoon leaving a ribbon trail in the bowl.
- Remove the bowl from the heat and stir in the butter. Strain the curd through a fine sieve into a large mixing bowl, then cover with cling film touching the surface of the curd so it doesn’t form a skin. Leave to cool to room temperature.
- Put the juice of the other 2 lemons into a small pan and heat until just simmering. Remove from the heat, squeeze the water out of the gelatine, then stir into the hot lemon juice until dissolved. Stir the juice mixture into the lemon curd.
- In a mixing bowl, whisk the cream to soft peaks, then gently fold into the lemon curd. In a large, spotlessly clean bowl whisk the egg whites until they form stiff peaks when the whisk is removed then, using a large metal spoon, fold into the lemon mixture. Gently spoon the mixture into 8 glasses and chill for 3 hours.
- Meanwhile, make the candied lemon. Slice the whole lemon into 3mm rounds using a sharp knife. Bring a pan of water to the boil and cook the slices for 30 seconds. Transfer with a slotted spoon to kitchen paper to drain, then repeat.
- Put 250ml cold water and the remaining 300g sugar into a pan over a medium heat. When the sugar has dissolved, add the lemon slices, reduce the heat and cook for 15 minutes. Lay out the slices on a tray lined with baking paper to dry.
- Serve the chilled mousses with the candied lemon and ginger biscuit pieces.
- If you prefer a more tart mousse, don’t sieve the lemon curd after cooking (step 3), but be extra careful not to curdle the egg.
- Make the mousse up to 24 hours ahead and keep covered in the fridge. It’s best to make the candied lemon just before serving.