In a medium saucepan, bring the chicken broth to a simmer, then keep warm over low heat.
In the same large braiser used to cook the mushrooms, melt 2 tablespoons of butter over medium heat. Add the minced shallot and cook for 2-3 minutes until softened and translucent.
Add the arborio rice and stir with a wooden spoon to coat each grain in the butter, making all the grains shiny. Toast the rice for about 1 minute.
Add the white wine and stir until it is absorbed into the rice.
Add 1 cup of warm broth while stirring. Once the broth has been absorbed (the bottom of the pan will be exposed when you drag your spoon across), add another cup. Continue adding broth, 1 cup at a time, stirring frequently and allowing it to absorb before adding more. This process will take about 20-25 minutes. The rice should be creamy and just slightly al dente. It should have the texture of slow-moving lava and not be a stiff ball.
Once the rice has reached the desired doneness, turn off the heat. Stir in ⅔ of the cooked mushrooms, truffle oil, the remaining 2 tablespoons of butter, and Parmigiano Reggiano. Stir until all the cheese and butter have melted. Season to taste with salt and pepper.
Ladle the risotto into bowls. Top with the remaining mushrooms, extra Parmigiano Reggiano, and chopped fresh parsley.