Put the unpeeled potatoes into a pan of cold water (slightly salted) and boil them for 20-25 minutes or until tender. Potatoes should be roughly of the same size so that the boiling time is the same for them all.
Generally speaking, the potatoes should be ready when the skin starts showing some cracks. Try to prick the potatoes with a fork and if you do not find any resistance, then the potatoes are ready for the next stage.
Drain the potatoes and put them onto a kitchen towel or whatever is practical for you.
Peel the potatoes.
Mash the potatoes.
It is easier to mash the potatoes when they are still hot, however, after mashing them, leave the mash to cool down for about 10 minutes. During this time, some of the water absorbed during the boiling will go away in the form of steam. The less water we have in the mash, the less flour we will use during the kneading.
Spread some flour onto the work surface to avoid the mashed potatoes sticking to it.
Put all your mashed potatoes onto the work surface.
Crack the egg into the bowl
Put the egg into a small bowl and whisk it for few seconds. We are not going to add the whole egg into the potato mixture otherwise the mixture will be too wet and will require too much extra flour to complete the dough (excessive flour will make the gnocchi stodgy). Better to have the egg in a bowl and to add what we need, taking, initially, just a couple of spoonfuls of it.
Add half of the flour and mix with your hand.
Then, as I said before, add just a couple of spoonfuls of egg and add the rest of the flour.
Knead the mixture for 5-7 minutes and if you think it is too dry, then you can add an extra spoonful of egg to bring the dough to the right consistency.
The final dough should be smooth and elastic (not sticky).
Cut the dough in 4-5 pieces as shown in the picture.
With every piece you have cut, make a ball.
Flour the work surface lightly. Then, press and roll the ball onto the surface to make long sausage-like strips.
The sausage should be about as thicker as your thumb.
When the long sausage is ready, it’s time to cut it.
Cut the sausage in about 2 1/2 cm (1”) long pieces.
The cut pieces should be laid onto the lightly floured work surface and separated.
Take the small pieces and make small gnocchi with them.
The gnocchi are then ready to be boiled. Normally, I boil the gnocchi straightaway but if you want to do that later (after few hours), separate them onto a floured cardboard tray and put them in the fridge.
Being the rolling process...
Rolling the gnocchi onto the fork prongs will make grooves on their surface. This is a good way to retain more sauce around their surface. If you want to do a top job, I suggest you use a grooving board specifically made for this purpose.
Gnocchi with grooves.
Take a large pan of salted water and bring to the boil. When the water is gently boiling, put the gnocchi into the pan and wait!
The gnocchi will be cooked when they start floating (it should take a couple of minutes). Leave them to float for a further 30 seconds.
Take them out with a slotted spoon and put them quickly into the saucepan containing the tomato sauce (this has to be hot).
To do this, you should have prepared the tomato sauce before and kept it ready for this final stage.
Also. You should have washed few leaves of fresh basil and patted dry with kitchen paper.
Gently toss the gnocchi in the saucepan for about 20-30 seconds and add the basil leaves. Serve it immediately.
Sprinkle with freshly grated Parmesan cheese.