Preheat your oven to 180°
Place your ready rolled puff pastry sheet on an oven tray lined with parchment paper.
Using a sharp knife, score a 2cm border around the edges of your pastry.
Prick the entire centre of your pastry with a fork.
Whisk together your egg and milk, then brush the entire surface of your puff pastry with this mixture.
Place your puff pastry in the oven to cook for 15 minutes or until golden brown.
Whilst your pastry is baking, in a blender combine the feta, yoghurt, garlic and dill. Whip for 3-4 minutes until light and fluffy.
Once baked, press down the centre of the puff pastry lightly using a spoon. Spread over your whipped feta, sparing the borders.
Layer on your sliced tomatoes, season with flakey salt, freshly cracked black pepper and optionally a drizzle of chilli oil and balsamic glaze.