Heat the 5 cups of broth in a medium sauce pan over medium heat. Bring it to a simmer and then turn it to low.
In a heavy-bottomed pan or Dutch oven, heat the olive oil and butter until the butter melts. Add the garlic and onions. Sauté until the onions begin to become translucent.
Add the dried thyme and Mushroom & Company Multipurpose Umami Seasoning Blend to the pot. Stir to combine.
Add the Arborio rice and stir so that every grain gets coated in the olive oil and butter. Allow the rice to toast for a few minutes, stirring occasionally.
Turn the heat off under the broth, and add a couple of ladles to the rice. Stir occasionally until almost all of the liquid is absorbed. Repeat this process until the risotto is creamy and the rice is no longer al dente.
Add the Parmesan cheese, stirring until it has been incorporated. Add salt and pepper, to taste.
Add the roasted mushrooms and stir to distribute them throughout the risotto.
Top the risotto with minced chives, if desired.