Three-cheese pides with egg and salsa verde

Method

1. For the salsa verde, combine the mustard, lemon juice and vinegar in a bowl and slowly whisk in the olive oil to thicken. Stir in the remaining ingredients, season, then set to one side.
2. For the cheese sauce, melt the butter in a heavy-based pan over a medium heat, then whisk in the flour to form a paste (or roux). Slowly pour in the milk, roughly 100ml at a time, whisking continuously. Turn down the heat to low medium and simmer for 10-15 minutes until thickened, then stir in the cheeses and season with salt to taste. Set aside, keeping warm until needed.
3. Heat your oven to its highest possible setting. (If you have a pizza oven, heat it to 350-400°C.) Put a pizza stone or large baking sheet in the oven to heat up.
4. Lightly flour a work surface and roll out a dough ball to an oval shape, about 35cm x 15cm. Spread the cheese sauce down the length of the base, leaving
   a 2.5cm border. Use a spoon to indent a small well in the middle for an egg yolk. Fold the sides of the pide inward, crimping the dough firmly at each end.
5. Dust a pizza peel with some flour and very carefully transfer the pide onto it. Or use a flour dusted or baking paper-lined baking sheet instead.
6. Transfer the pide to the hot pizza stone/baking sheet in the oven, then bake the pide for 3-4 minutes (in a pizza or wood oven) or 6-8 minutes in a standard oven until golden brown and crisp around its edges, rotating it halfway through to ensure it cooks evenly. About 2 minutes before the pide is finished, crack an egg into the centre, rotate the pide and return it to the oven.
7. Remove the pide from the oven and brush the edges with melted butter. Sprinkle with za’atar and salt flakes, then dollop the salsa verde all over and finish with a final drizzle of olive oil. Repeat with the remaining pides. Slice and serve immediately.