Pastry time! Work butter into flour with the tips of ya fingers. Add water and get it to all come together in a disc. Wrap with glad wrap if you have it and pop in the fridge freezer for 20 minutes.
Blind bake! Roll out pastry to lt 0.5cm and place into tart case. Cover in baking paper and cover that in rice. Bake for a bit at 180 degs, until the pastry is cooked.
Make the custard! Whisk together eggs, juice of all the lemons, zest of one of the lemons and the sugar, then slap that into your (baked) pastry case. Bung her back into the oven until the custard firms up and ceases to wobble.
Cool and fridge overnight.
Notes
We don't want wobbling. So keep baking. If there's too much wobble.