Add oil to wide, shallow frying pan over medium heat pan and when warm, add the leeks and cook for 4 mins until softened. Add cumin, garlic and chilli (if using) for the last minute or so. Add spinach, as much as will fit at a time, stirring until wilted.
Stir in the peas and herbs and season to taste. Cook for a few minutes until fragrant, then sprinkle over the feta. Make eight indentations in the mixture, breaking an egg into each. Cover and cook for 8 minutes or until the whites are set but the yolks are still runny.
Season the eggs with chipotle or chilli flakes and scatter with remaining mint leaves.
Serve immediately with flatbread.