There are step by step photos in post above plus lots of other info!
Preheat oven to 200c (390f)
Place the potatoes on a baking tray and bake for 1 hour or until easily pierced with a sharp knife. The skin should have puffed up.
Leave them just long enough to cool so you can touch them without scalding your hands, 10 minutes or so.
Cut them in half and peel the skins off. Push the pieces through a potato ricer onto a baking tray lined with a tea towel or paper hand towels. Let it cool slightly.
Mix the salt and flour into a bowl.
Tip the potato into a bowl or onto your bench top. Drizzle the egg over and then sift the flour over top.
With your hands (or a fork in a bowl) gently bring the mixture together.
Use your hands to scrunch it into a ball and lightly knead for 1 - 2 minutes to bring it together. No more than that!
You aren't looking for a perfect smooth dough here, it will be dimpled and a little rough looking.
It will be slightly sticky but shouldn't stick to any surface so sprinkle more flour if it's super sticky.
Divide into 6 - 8 pieces and then roll each piece out into a long 2cm wide log on a wooden board.
You need to start in the middle with your hands flat against the board and gently pull as you work your hands outwards.
Cut the log into 2cm long pieces. I prefer to leave them as little pillow shapes but you can gently roll them on a gnocchi board or fork if you want ridges.
Cook in well salted boiling water and pull them out about 30 seconds after they float to the surface.
I love to pan fry them to crisp up the outside or you can just add them straight into any sauce you like.