Preheat the oven to 170C/320F/Gas 3. Lightly grease a baking tray.
For the almond crumble, place all the dry ingredients into a free-standing electric mixer fitted with the paddle attachment. Mix briefly at medium speed, then add the butter and mix until a crumbly dough forms.
Crumble the dough onto the greased baking tray and place in the oven for 20 minutes, or until golden-brown, and then remove from the oven and set aside to cool.
For the gooseberry jelly, place the gooseberries, sugar, lemon juice and 200ml/7fl oz water in a bowl and set it over a pan of simmering water, making sure the water doesn’t touch the base of the bowl. Cover with a lid and leave for one hour.
Pour the mixture through a fine sieve into a bowl, discarding the solids.
Measure out 400ml/14fl oz of the gooseberry juice, pour into a pan and heat to near-boiling point. Remove from the heat.
Squeeze out any excess water from the softened gelatine and add the gelatine to the juice. Whisk until the gelatine dissolves. Divide the mixture between eight round-bottomed glasses and leave it to cool. Place in the fridge to set.
For the poached nectarines, put the sugar and wine into a heavy-based pan, add 500ml/18fl oz water and bring to the boil, stirring until the sugar is dissolved.
Gently drop the nectarines into the poaching syrup. Bring back to the boil over a medium heat, then turn the heat down, cover and cook at a bare simmer for 8-10 minutes, until the nectarines are tender when tested with a small, sharp knife.
Remove the pan from the heat and set aside to cool to room temperature.
Lift the fruit out of the syrup and pull off the skins, then return the fruit to the syrup and set aside, covered, at room temperature.
For the gooseberry fool, place the gooseberries in a heavy-based pan and add the sugar, lemon juice and zest and a tablespoon of water. Cook over a medium heat for about five minutes, until you have a moist compôte; the softened fruit should be bound in its juices, but with no excess liquid remaining. Remove from the heat and set aside to cool.
Pour the cream into a large bowl and add the vanilla seeds.
Add the icing sugar to the cream and whisk until the cream is rich and aerated, but still retains its fluidity. Gently fold in the gooseberry compôte with a rubber spatula. The finished fool should drop easily off the spatula – it must still be creamy, not a stiff, set mousse.
To serve, cut each greengage half into three wedges. Lift the nectarines out of the syrup and chop them into 1cm/½in pieces.
Divide the chopped nectarines equally between the glasses containing the gooseberry jelly, and divide all but two tablespoons of the almond crumble between the glasses.
Cover the crumble with a layer of gooseberry fool. Dress the sliced greengages in a little of the nectarine syrup, put them on top of the fool and finish with a fine sprinkle of the remaining crumble.