First of all start by cooking the pumpkin, see above post for suggested methods. (If you have the canned purèe, you're one step ahead).
In a pan, drizzle the olive oil and add the minced garlic clove. Turn on to medium heat. When it starts to sizzle, add the chopped Porcini mushrooms (after you carefully cleaned them) and sauté for a couple of minutes. Then add the rice and let it toast for 2 more minutes.
Pour the white wine and let the alcohol evaporate, then turn down the heat to low and add a cup of hot vegetable stock. Once the liquid is absorbed, add more stock and repeat until the rice is cooked.
Meanwhile, purée the pumpkin and add it to the risotto halfway through the cooking (about 8-10 minutes).
Add also the heavy cream and mix well. When the rice is "al dente" (it should still have a bite, but it shouldn't be crunchy) turn off the heat, add the finely chopped parsley, black pepper and finish with a tablespoon of butter and Parmesan cheese to make the risotto super creamy and delicious!