Start by bringing chicken broth to a simmer in a sauce pan on the side; this will remain on the stove throughout the entire cooking process.
Next, heat a little oil in a heavy bottomed skillet over medium heat; add the mushrooms and sauté for 3-4 minutes, then add garlic. Cook another minute or so, until cooked down and deliciously fragrant. Transfer mushrooms to a bowl on the side.
Now, using the same skillet, add 1 T butter and 1 T olive oil. Add arborio rice and give it a good toss to coat; cook for about 1 minute, until slightly golden & toasted. Ladle in 1/2 c broth, give it a stir and then leave it alone until broth is nearly absorbed (about 2-3 minutes).
Stir, add another 1/2 c broth, stir again, and leave alone until liquid is mostly absorbed (another few minutes). Repeat this process using all broth until 1/2 c broth remains (About 20-25 minutes total).
Turn off heat, add mushrooms back to pan, remaining 1/2 c broth, salt, and parmesan cheese; stir for 2-3 minutes, until creamy. Serve immediately in bowls with a drizzle of truffle oil, fresh parsley, and more grated parmesan.