Line a dish with parchment paper (24x34cm)
Preheat oven to 210°C
Fry chopped leeks and onions in olive oil for 5 minutes
Add frozen spinach, garlic, salt, pepper and herbs to the leeks and onions
Keep stirring until spinach is defrosted and liquid has evaporated
Set aside on a plate to cool
Roughly chop potatoes into big chunks (you can leave skin on)
Boil potatoes with salt until tender
Add feta to the spinach, leek and onion mixture and mix until combined
Whisk eggs, crème fraîche, mozzarella, salt, pepper and paprika together
Drain potatoes well and mix in butter or olive oil
Smash potatoes into the dish using the bottom of a jar and finish with a spoon to smooth
Bake potatoes for 12-15 minutes until golden and slightly crispy on the outside and edges
Remove from oven and add the spinach and feta mixture
Top with the egg mixture and optional grated cheese
Turn down oven to 200°C and bake for another 25-28 minutes
Enjoy hot or cold
