Mix all the spices for the advieh blend together in a small bowl.
Heat 2 tablespoons of the oil in a large heavy-bottomed frying pan. Add the onion and fry on a low heat for 10 minutes to soften and start to brown.
Heat the grill to medium.
Remove the onion to a plate and add the remaining tablespoon of oil to the pan. Turn the heat up, add the courgettes and fry in batches (if need be) until they have some colour, about 2 3 minutes per side.
Add the garlic, advieh spice mix and the fried onions. Fry for a further 2 minutes, stirring, then season with salt and pepper.
Whisk the eggs with the milk in a large bowl, stir in the chopped herbs and pour over the top of the courgettes. Cook very gently for a few minutes until just set on the bottom.
Finish under the grill until just set all the way through (test by gently tipping it sideways,
no runny egg should appear). Wait for at least 5 minutes before cutting into wedges to serve (Garnish with extra chopped chives and a pinch of paprika, optional)