In a frying pan heat oil and fry shallot over low heat till softened. Add radicchio and cook, stirring occasionally, till the radicchio is just wilted. Season with salt, cover and set aside.
For the risotto, heat oil in a large saucepan and fry leek till softened, Add the pumpkin and sage and cook over medium heat till it just begins to soften, about 10 minutes.
In the meantime the stock in a saucepan and keep it warm.
Add the rice to the saucepan and cook till it has absorbed the oil and looks glassy, about 2 minutes. Add the wine and let it evaporate. Start adding the stock, one ladle at a time, stirring well after each addition and adding the next ladle only when the previous one has been completely absorbed. Proceed in this way till the rice is completely cooked, about 18 minutes total.
Just before the risotto is fully cooked, add the radicchio mixture to the risotto.
Turn off the heat and add the cheese. Stir well and cover with lid. Leave to stand for 3 to 4 minutes before serving.