Bring a pot of salted water to a boil and cook the tagliatelle according to package directions until al dente, reserving 2 tablespoons of pasta water before draining.
While the pasta cooks, slice the chicken breast into thin strips and season with half of the sea salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat and sauté the chicken until golden and cooked through, then remove from the pan and set aside.
In the same skillet, add the sliced mushrooms and cook until they release their moisture and turn golden brown.
Add the minced garlic to the mushrooms and sauté for 30 seconds until fragrant, then stir in the fresh spinach until just wilted.
Reduce the heat to low and stir in the Greek yogurt, reserved pasta water, truffle oil, and the remaining salt and pepper to create a smooth sauce.
Add the cooked pasta and chicken back into the skillet, tossing gently to coat everything in the creamy truffle sauce.
Serve immediately topped with a sprinkle of parmesan cheese.