Step 1:- In a saucepan, heat the butter and sweat the leek with the ginger and thyme. Step 2:- Check for doneness, salt and set aside.
Step 3:- Put the leeks in equal quantities in the 4 ramekins and cover with the crème fraiche and salt lightly
Step 4:- Put the eggs on the cream, being careful not to break the yolk, and sprinkle with Gruyère cheese
Step 5:- Put the ramekins in the water bath and put in a preheated oven at 180 degrees for about 10 to 15 minutes, the eggs are ready when the white is just set