5: Divide mashed potato in two, salt and pepper the first half, then over a low heat add 100 g butter and 125 g cream while stirring constantly. Set aside.
6: Make the duchess potatoes: salt and pepper the other half of the mashed potato, add 3 egg yolks and 3 egg yolks.
7: Whip until nicely smooth and yellow.
8: Cook 125 g small pieces of bacon in a frying pan without fat, until they are cooked but not browned. Set aside.
9: Preheat your oven to 180°C or 356°F. Start assembling the ramekins: butter the bottom, and put in a layer of mashed potao about 1 cm or 0.5 inch deep.
10: Add a layer of cooked leek.
11: Add some bacon.
12: And finish with a layer of duchess potatoes, if possible by using a forcing bag (it's prettier).
13: Cook in the oven until duchess potatoes are golden brown (about 20 minutes).
14: Serve hot.
Remarks
If you don't have a forcing bag, spread the duchess potatoes on top of ramekin, and shape with a fork.