Prepare the mushrooms: Drain well if using canned mushrooms. Cut fresh or drained canned mushrooms into quarters.
Sauté the mushrooms: In a large pan over high heat, add olive oil and sauté the mushrooms until they start to brown.
Add onion and garlic: Add the onion cut into large pieces and two cloves of chopped garlic to the pan without stirring immediately.
Add rice and sauté: Add the arborio rice to the pan and sauté lightly, then deglaze with white wine.
Gradually add water and broth: Slowly add boiling water and vegetable broth, stirring occasionally, until the rice is cooked.
Final touches: Turn off the heat. Add frozen butter and stir until melted. Optionally, add truffle oil. Add grated parmesan cheese and stir until the risotto is creamy.
Serve: Serve the risotto with additional grated parmesan, chopped chives, a drizzle of olive oil, and freshly ground pepper to taste.