3: Use the same pan to fry the white parts of the spring onions, adding a little oil if necessary. Salt and pepper, then cook for 1 or 2 minutes without colouring. Set aside.
7: Put the mashed potatoes into a mixer bowl, start kneading on slow speed...
8: ...and mix in 4 egg yolks, one at a time, then salt and pepper. Knead until smooth and evenly mixed.
9: Finish by incorporating the ham strips, the cooked onion, the raw onion (green) and the finely chopped chives.
10: Preheat the oven to 390°F (200°C). FIll a non-stick tin or mould with the mixture and smooth the top with the back of a spoon or soft spatula.
11: Bake for about 30 minutes.
Remarks
You can use whatever kind of ham you prefer: dry-cured or smoked, or even use bacon bits (lardons) instead. If you don't have spring onions, or they are out of season, use a normal onion or shallots, but increase the amount of chives or add a little chopped parsley.