For the pesto, put all the ingredients except the oils in a food processor. Add half the olive oil and whizz until the kale is finely chopped. Stir in the remaining olive oil and basil oil (if using), then season with salt, pepper and extra lemon juice as needed. Set aside while you make the risotto.
Heat the oven to 180C fan/gas 6, then make the risotto - melt the butter in a large saucepan over a medium heat. Add the oil, leeks and a pinch of salt, then cover and cook, stirring regularly, for 8 to 10 minutes until very soft. In a separate pan, heat the stock over a low heat.
Add the garlic to the leeks and cook for 2 minutes, then add the rice and stir to coat in butter/oil. Increase the heat to high, then pour in the wine and simmer for 2 to 3 minutes until absorbed. Reduce the heat to medium high and gradually add the hot chicken stock, one ladleful at a time, stirring continuously. Wait until each addition has almost all been absorbed before adding the next. Continue until you’ve added all the stock and the rice is al dente (still has some bite – about 15 minutes). Stir in the grated cheese, then season with salt and lots of black pepper.
While the risotto cooks, arrange the prosciutto on a large baking sheet and bake for 10 to 12 minutes until crispy. To serve, swirl a few tbsp of pesto into the risotto, then top with prosciutto shards, extra pesto and grated cheese.