2) Using a potato masher, mash the potatoes onto a greaseproof-paper-lined baking sheet in an even layer (do not pile the mashed potatoes into mounds). Set aside to cool.
3) Transfer the potatoes to a large bowl and, using a rubber spatula, gently mix in the flour, yolks, salt, nutmeg and pepper until just combined and a soft dough is formed. Do not over mix the dough or the gnocchi will be unpleasantly dense.
4) On a well-floured work surface, turn out the potato dough and divide into 6 equal parts. With the palms of both hands gently roll each part into a "rope" 2cm in diameter. Using a sharp knife cut each "rope" at an angle into 2cm long pieces.
5) To shape the gnocchi, hold a salad fork in one hand so it rests on the work surface at a 45-degree angle with the tines curving up. Place a piece of the dough at the top of the tines and hold it in place with your free thumb. In one gentle motion, quickly press and roll the dough along the tines. The gnocchi should have a small dent in one side and shallow grooves on the other, perfectly suited for holding a sauce. Repeat with the remaining pieces and transfer to a lightly floured baking sheet pan. Store in the refrigerator for at least 1 hour and up to 24 hours before cooking.
6) When ready to serve, bring a large pot of salted water to a boil. In a medium skillet, heat the double cream over a medium-high heat until just hot. Remove the cream from the heat and whisk in the pesto. Using a rubber spatula, scrape the pesto mixture into a large bowl. Set aside in a warm spot.
7) Add half the gnocchi to the boiling water and cook for 1 1/2 minutes or until they rise to the top. (Take care not to overcook the gnocchi or they can disintegrate during cooking.) Using a slotted spoon or strainer, transfer the gnocchi to the bowl with the pesto and toss. Repeat with the remaining gnocchi.
8) If the sauce seems too "tight" add some of the cooking water a tablespoon at a time until a saucy consistency is reached. Season with pepper to taste. Divide among warm bowls and serve immediately.
Cook's Note: If rolling the gnocchi is intimidating, skip the shaping the gnocchi with a fork. Cooking them unshaped produces a fine gnocchi as well.
For the basil pesto:
1) In a food processor, combine the basil, pine nuts, Parmesan, garlic and salt and puree.
2) While the motor is running, drizzle in the oil until incorporated. Season with pepper to taste. Use immediately or store in the refrigerator with a piece of cling film placed right on the surface of the pesto to prevent discolouration, for up to 3 days, or freeze for up to 1 month.