Dissolve stock in 3⁄4 l hot water. Peel and finely dice onions and garlic. Heat 2 tablespoons of oil in a saucepan. Sauté onions and garlic in it until transparent. Add rice and fry for 1-2 minutes while stirring until the
They should become glassy, but they must not take on any colour.
Deglaze with wine. Allow to evaporate at medium heat while stirring for about 1 minute. Add hot stock until the rice is covered. As soon as the rice has absorbed the liquid, add stock again.
Simmer rice open at low heat for 25-30 minutes until al dente. Stir over and over again so that nothing sticks.
Preheat the oven in between (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Line a baking tray with baking paper. Peel sweet potatoes and cut them into pieces of approx. 1.5 cm. Mix with salt, chilli and 1 tbsp. oil.
Spread on the sheet. Cook in a hot oven for about 15 minutes, turning after about 8 minutes.
Stir a good half of the sweet potatoes, mascarpone and grated hard cheese into the risotto. Season to taste with salt and pepper.
Wash sage, shake dry and pluck leaves. Heat 1 tablespoon of oil in a frying pan. Fry the sage and pine nuts for about 2 minutes. Arrange on the risotto with remaining sweet potatoes.