Preheat the oven to 180°C, gas mark 4.
Heat the rapeseed oil in a large frying pan and fry the leeks for 5 minutes until softened. Spread the bread with the cream cheese and cut each slice into quarters. Place half in the base of a heatproof dish, cheese side up. Scatter half the leeks over the top.
Mix the eggs, milk and seasoning together and pour half over the leeks, repeat with the remaining bread and leeks, then pour over the remaining egg mixture. Bake for 25 minutes until golden and set. Serve with sautéed green vegetables.