Pour the stock in a saucepan and bring it to simmer. Keep it at a constant low heat.
In a big flat pan, add butter and a little bit of oil along with grated garlic. Stir and add chopped leaks. Then, season it with salt and pepper. Cook for a few minutes at medium heat until it softens.
Drop the risotto rice, stir and let it cook for a minute or two. Sprinkle a little bit of salt and pour wine. Give it a mix.
Once the wine is absorbed, pour a ladle of the warm stock and give it a stir. Let it cook in medium heat until the stock is absorbed and then, add another ladle of the stock. Repeat the steps until the rice is cooked to al dente. It should have a mild crunch but it shouldn’t be raw. Finally, add Parmesan cheese and cream, give it one last mix and cook for one more minute. Keep it aside to cool down completely.
to prepare the sautéed mushrooms
Add oil and grated garlic in a hot pan. Scatter the chopped onions and cook until they're translucent. Now, add the mushrooms, season with salt and cook until the mushrooms are cooked though and softened. Add sun-dried tomato pesto or finely chopped sun-dried tomatoes. Stir and cook for a minute. Finally, add Parmesan cheese, chili flakes, dried oregano to it and give a final mix. Once done, keep it aside to cool down completely.
to prepare the mushroom arancini
Once the rice is cooled completely, crack 1 egg and add 1-cup breadcrumbs to it. Give it a mix.
Now, take 1½ tablespoon of risotto and flatten it in your palm. Drop a little bit of the mushroom mixture in the center and pinch on all the sides to form a ball. Rub in breadcrumbs and keep aside. Once all the risotto balls have been stuffed, keep it in refrigerator for about 30 minutes.
For deep-frying, add enough oil in a deep saucepan. Once the oil is hot enough, drop the risotto balls and let it fry until golden brown. It should take about three minutes.
Serve hot with your choice of dipping sauce.
Notes
If you find it hard to stuff the filling, then just make the risotto balls and let it rest in the refrigerator for about an hour. That will make it easy to flatten it, stuff and then pinch all the sides to form the arancini.