Steam or boil the sweet potato until tender. Drain well and mash until smooth, cool slightly then stir through the yolks, Parmesan and seasonings.
Gradually mix in enough flour until the dough is soft and pliable, but not too sticky. Knead the dough on a floured surface until smooth. Divide into 4 portions and roll each into a 2cm thick rope, then cut into 2cm long pieces. Shape each into a round and press with the back of a fork. Set aside.
Place the tomatoes on a paper lined baking tray, spray with oil and sprinkle with salt. Bake in a moderate oven 180°C for 10 minutes. Keep warm.
Heat the oil in a frypan and sauté the spring onions and garlic for 3 minutes. Add the PHILLY, stock and chopped sage, stir until smooth and simmer for 2 minutes. Season to taste.
Cook batches of gnocchi in a large saucepan of boiling salted water, removing with a slotted spoon as they float to the surface. Toss the cooked gnocchi in the sauce with the tomatoes and cook a further 2 minutes or until heated through. Spoon into serving bowls, garnish with pine nuts and extra sage. Serve immediately.Visit PHILLY for more delicious recipe ideas.