In a blender, add the eggs, sugar, lemon juice and lemon zest. Whizz on a high speed until smooth and frothy, then slowly pour in the olive oil with the motor still running.
Set a heatproof bowl over a pan of simmering water and add the lemony egg mixture. Using a spatula, gently stir continuously, scraping the bottom of the bowl until it starts to thicken. Change to a whisk, whisking continuously until it has a dropping consistency. This will take about 10 minutes and will seem slow but will turn thick very suddenly.
Remove from the heat and set aside to cool, covering the surface with clingfilm. Transfer to the fridge and leave for at least three hours, preferably overnight.
In a small saucepan, add half the blueberries along with the lemon juice and 1½ tbsp caster sugar. Bring to the boil and then simmer on a medium-low heat for 2 minutes, stirring occasionally, until thickened and some of the berries have burst. Remove from the heat and leave to cool, then transfer to a fridge.
Place the shortbread in a bag and crush into fine crumbs with a rolling pin. Combine with the melted butter until completely covered. Transfer to the fridge. Beat the cream cheese with the remaining 1 tbsp of caster sugar, then briefly beat in the cream until combined and smooth.
Once everything is prepared and chilled, layer in your serving glasses of choice along with the lemon olive oil curd, the remaining blueberries and the lemon zest.