This is so easy and so inexpensive to make. And you wouldn't believe what they charge for it in restaurants!
For four serves, you need:
8-10 washed potatoes
Plain flour....hard to say how much, but about a cup or two
Bake the washed potatoes in a preheated 175C oven, till soft when pierced. Allow to cool.
Peel skin off and mash well. Despite all you've read and heard, a few lumps are ok. Don't use any milk or butter.
Add 2 eggs and mix with a fork.
Add enough plain flour to form a sticky dough...about a cup or a bit more, and mix lightly with a fork. It should look like a cookie dough.
Dust the bench with flour and take a quarter of the dough and roll it into a long cigar shape. Cut the cigar into thumbnail sized chunks and lay on a large platter. Make indentations with a fork to help the sauce adhere. Repeat with the remaining dough.
Bring a large pot of salted water to the boil and cook the gnocchi in small batches so they don't stick together.
Get out your bowls, and put a knob of butter in each, and add the gnocchi as it's cooked. Two minutes in the water is enough for thumb sized gnocchi. Toss the gnocchi in the butter as it melts and add salt, pepper and grated fresh Parmesan. That's it.
I use whatever gluten free flour I have I hand and it always works. The key is to bake the potatoes so they remain dry, only add enough flour to get a sticky dough, don't knead, and only mix the dough enough to mix the flour through.