01 - Heat olive oil and butter in a large heavy-bottomed skillet over medium heat. Add chopped onion and sauté until translucent, about 3 minutes.
02 - Stir in mushrooms and cook until softened and lightly browned, approximately 7 minutes. Add minced garlic and cook for 1 minute, stirring frequently.
03 - Add Arborio rice to the pan and stir continuously until edges turn translucent, roughly 2 minutes.
04 - Pour in white wine and cook, stirring, until almost fully absorbed.
05 - Ladle in 1 cup of warmed chicken broth, stirring regularly until the liquid is absorbed. Continue adding the remaining broth, 1 cup at a time, allowing each addition to be absorbed before pouring more. This process should take about 25 minutes.
06 - Once rice is creamy and tender yet al dente, fold in Parmesan cheese and fresh thyme leaves. Season generously with salt and pepper.
07 - Transfer risotto to serving plates and garnish with additional thyme or Parmesan, if desired.