Bring a medium pot of salted water to a boil and cook the whole wheat penne according to package directions until al dente.
While the pasta cooks, reserve 2 tablespoons of the starchy pasta water, then drain the pasta and set aside.
Season the chicken breast with half of the sea salt and black pepper.
Heat the avocado oil in a non-stick skillet over medium-high heat and sear the chicken for 5-6 minutes per side until cooked through, then remove and slice into strips.
In the same skillet, add the sliced cremini mushrooms and minced garlic, sautéing for 4 minutes until the mushrooms are golden and tender.
Lower the heat to low and whisk together the Greek yogurt, reserved pasta water, truffle oil, and remaining salt and pepper in the skillet with the mushrooms.
Toss the cooked pasta and sliced chicken into the sauce, stirring gently to coat everything evenly without curdling the yogurt.
Serve immediately topped with a sprinkle of parmesan cheese.