Sauté leeks and garlic in olive oil in a large heavy-based pan (add chilli flakes, if using).
Add asparagus and sauté for one minute. Add peas and sauté for another minute. Stir in the baby spinach until just wilted.
Make four wells in the vegetable mixture. Crack an egg into each well. Place the lid on the pan and cook for a couple more minutes, until eggs are cooked through.
Serve immediately with some pieces of trout (optional) and a squeeze of lemon juice.