Preheat your oven to 400°F and line a small baking sheet with parchment paper.
Toss the sliced cremini mushrooms with the olive oil, half the sea salt, and half the black pepper; roast for 15 minutes until golden and tender.
Bring a pot of salted water to a boil and cook the tagliatelle according to package instructions until al dente, reserving 2 tablespoons of the pasta water before draining.
Season the chicken breast with the remaining salt and pepper, then sear in a non-stick skillet over medium-high heat for 5-6 minutes per side until fully cooked.
Remove the chicken from the pan, let it rest for 2 minutes, and then slice it into thin strips.
In the same skillet, add the minced garlic and diced shallots, sautéing for about 1 minute until fragrant and translucent.
Deglaze the pan with the chicken broth and reserved pasta water, stirring to incorporate any flavorful bits from the bottom of the pan.
Add the cooked pasta, roasted mushrooms, and sliced chicken to the skillet, tossing gently to combine.
Remove from heat and drizzle the truffle oil over the pasta, tossing once more to create a glossy finish.
Garnish with freshly chopped parsley and serve immediately.