Preheat the oven to 320 degrees Fahrenheit and boil a kettle of water.
Step 2
Lightly butter 2 large ramekins. Heat the remaining butter in a saucepan over a low/medium heat. Finely slice the leeks and add to the pan. Sauté in the butter for 3-4 minutes until tender.
Step 3
Divide the leeks between the two ramekins.
Step 4
Crack one egg on top of each and season with salt and pepper.
Step 5
Sprinkle over the cheese.
Step 6
Spoon over the crème fraiche.
Step 7
Arrange the ramekins in a deep oven tray and half fill the tray with the boiling water.
Step 8
Transfer to the oven for 15-20 minutes until the eggs are cooked to preference.