Melt 3 tablespoons butter with olive oil in large saucepan over medium heat. Throw in the chopped onions and finely chopped garlic. Cook the ingredients soft.
Add in the mushroom pieces and stir-fry for a minute, before seasoning the dish with salt and black pepper. Cook the mushrooms for 2-3 minutes on medium heat.
At this point, you can add the rice. Stir fry the rice for a minute on high heat so that the aroma is released.
Deglaze with white wine.
Next, pour in one ladle of the broth.
Season with thyme and rosemary. Mix well and keep on medium heat.
Continue to pour in one ladle at a time of broth. After each ladle of broth, mix the content and let it cook down, then add another ladle of broth. Continue the process until you have used up all the broth and the rice is cooked through.
Add and mix in the truffle oil and Parmigiano Reggiano Cheese.