Prick the potatoes all over, then bake for 1 hour, or until tender. Leave to cool for 15 minutes, then peel and mash, or put through a ricer. Do not use a blender or food processor.

Mix in egg yolks and parmesan, then gradually stir in flour. When the mixture gets too dry to use a spoon, work with your hands. Once a loose dough forms, transfer to a lightly floured surface and knead gently. Work in enough extra flour to give a soft, pliable dough that is damp to the tough but not sticky.

Divide dough into six portions. Working with one portion at a time, roll out on the floured surface to make a rope and 1.5 cm thick. Cut the rope into 1.5 cm lengths. Take one piece of dough and press your finger into it to form a concave shape, then roll outer surface over the tines of a fork to make deep ridges. Fold outer lips in towards each other to make a hollow in the middle. Continue with the remaining dough.

Bring a large saucepan of salted water to a boil. Add the gnocchi in batches, about 20 at a time. Stir gently and return to a boil. Cook for 1-2 minutes, or until they rise to the surface. Remove with a slotted spoon, drain and out in a greased shallow casserole or baking tray. Preheat the oven to 400 degrees F (200 degrees C).

To make sauce, melt the butter in a small frying pan and fry the bacon until crisp. Stir in the sage leaves and cream. Season and simmer for 10 minutes, or until thickened.

Pour sauce over the gnocchi, toss gently and sprinkle parmesan on top. Bake for 10 minutes or until parmesan melts and turns golden.

*When cooking the potatoes for gnocchi you want to keep them as dry as possible- too much moisture will result in a heavy dough. Floury potatoes have a low moisture content and baking the potatoes in their skins keeps them drier than boiling.