Sift the flour, sugar and salt into a large bowl and stir in the crushed chamomile leaves. Add the butter and use your fingertips to rub it into the flour mixture until it resembles breadcrumbs.
In a separate bowl or cup, mix the egg yolk and water, then add to the butter mixture. Mix with a butter knife until it forms a loose dough (add a little cold water sparingly, if required), then knead until smooth.
To make the chamomile pastry in a food processor
Alternatively, make in a food processor: add the flour, sugar, salt, crushed chamomile tea leaves and butter to the bowl of the food processor. Pulse until it forms small crumbs. Mix the yolk and water and add to the food processor. Whiz until it all comes together in a ball.
For both methods
On a floured surface, roll out the dough to 3mm/ ⅛ inches thick and use it to line the prepared pie pan. Place in the fridge and chill for 30 minutes.
Preheat the oven to 190C/375F. Place the pie tin onto a baking tray. Line the base of the pastry case with baking parchment and fill with baking beans (or uncooked rice), then bake, on the the tray, for 15 minutes.
Remove the baking beans and parchment, then cook for another 5 minutes, or until just starting to turn golden. Remove from the oven and leave to one side.Reduce the oven to 160C/320F.
For the filling
In a bowl, mix the whole eggs and extra egg yolk with the sugar until smooth, then stir in the cream. Add lemon zest and juice and gently mix - the filling will thicken.
Pour the filling into the pastry case and carefully transfer the pie tin on the tray to the oven and bake for 35 minutes or until nearly set, but the centre is still a bit wobbly. Don’t overfill as the pastry could shrink a bit. Allow to cool completely.
For the chamomile-infused powdered sugar
Whiz the granulated sugar and chamomile tea in a blender until it turns into a fine powder. Dust onto the completely cooled lemon tart.
Tip: pour half of the filling into the pastry case, transfer the rest of the filling to a jug and finish filling the case when it’s in the oven, to avoid spilling.