Prepare a tomato sauce by heating the olive oil gently with the garlic. Let the garlic soften but not colour. At the slightest hint of colouring,add the canned tomato,along with about 200ml of water,a pinch of salt and half the basil leaves. Bring to a simmer and cook,uncovered,for 20 minutes. Set aside until needed.
For the gnocchi,rinse the potatoes of any dirt but keep them whole with skins on. Place on a tray and roast until a fork easily pierces the potatoes,about 35 minutes for medium-sized potatoes (it helps if the potatoes are of a similar size).
Peel the skins off the potatoes while still hot (try this with rubber gloves or by holding the potato with a fork with one hand and using the other hand to peel with a small,sharp knife) and immediately mash until perfectly smooth,spreading out the mashed potato on a tray or chopping board to allow the steam to escape quickly. Continue with the rest of the potatoes,then collect the cooled,smooth mashed potato into a wide bowl or clean surface.
Add the egg and one teaspoon of salt to the potato and begin to beat well to incorporate fully. Begin incorporating the flour and knead it to a smooth dough until it just comes together. Turn onto a floured surface and,taking fist-sized portions of dough,roll into a log about 1 1/2cm wide,then cut the log into 2cm long pieces.
Dust liberally with flour and place the gnocchi pieces onto a sheet of baking paper. Continue with the rest of the gnocchi mixture.
Bring a large pot of water to boil. Add one teaspoon of salt to the water and turn to a simmer. Tip the gnocchi into the pot (a tip:taking the baking paper by two opposite corners,simply place the entire sheet of paper – yes,paper and all – into the water then pull the paper out).
Cook two to three minutes or until the gnocchi begin to float and feel springy. Drain the gnocchi immediately and add to the tomato sauce,tossing to coat,then pour the gnocchi into a baking dish.
Sprinkle the top of the gnocchi with the parmesan and dot the top with the mozzarella and the rest of the basil. Place in oven at 180C for 15-20 minutes or until the top is golden brown and bubbling. Serve immediately.
Emiko Davies is a food writer,photographer and blogger.