For the syllabub:

1. Chill a bowl in the fridge until it is very cold. 
2. In a separate bowl, combine the wine, sugar, lemon zest and juice, and stir to dissolve. Refrigerate this mixture for at least 30 minutes.
3. Pour the cream into the chilled bowl and whisk the mixture until it barely forms soft peaks. Do not over beat. Add the chilled wine-lemon mixture gradually to the cream, whisking continuously, until it forms soft peaks. Refrigerate the syllabub until you are ready to serve the dessert.

For the nectarines:

1. Place the nectarine slices into a large bowl. Set aside. 
2. Warm the butter, sugar and vanilla paste in a small saucepan over low heat.  When the sugar has dissolved, pour the mixture over the nectarines and toss to coat. 
3. Heat a large skillet over medium-high heat. Cook the nectarine slices for 3-4 minutes, turning them occasionally, until just browned and starting to render their juice. Divide the nectarine slices and pan juices among eight serving bowls or jars and spoon some of the syllabub on top. Serve immediately.