In a large skillet, add 2 tablespoons butter over medium-high heat.
Add mushrooms and cook until golden brown, about 15 minutes. Remove mushrooms from skillet and transfer to a clean plate.
While mushrooms are cooking, add vegetable broth to a pan and set it over medium-low heat.
Add remaining 2 tablespoons of butter to skillet over medium-high heat.
Add diced onion, season with salt, and cook until translucent, about 5-7 minutes.
Add garlic and cook one more minute.
Add arborio rice, stirring well to combine, and let it cook for 1 minute.
Add wine to the pan and stir to combine, cooking until it has absorbed.
Add the warm vegetable broth in ½ cup increments, stirring frequently and letting the rice absorb the liquid before adding more.
Once all of the broth has been used, stir in the cheese.
Top with mushrooms and chives and (optional) truffle salt.
Serve and enjoy!