Preheat your oven to 400°F (200°C). Toss sliced mixed mushrooms with 1 tablespoon olive oil, salt, and pepper on a baking sheet. Roast for 15-18 minutes, stirring halfway, until golden and caramelized.
Bring a large pot of salted water to a boil. Cook tagliatelle until al dente, about 7-9 minutes. Reserve 1/4 cup pasta water, then drain.
Heat remaining 1 tablespoon olive oil in a large skillet over medium heat. Sauté minced garlic for 1-2 minutes until fragrant but not browned.
Add vegetable broth to skillet and simmer for 3-4 minutes to reduce slightly. Stir in roasted mushrooms, coating them with the broth.
Add drained tagliatelle to the skillet and toss gently, adding reserved pasta water a tablespoon at a time if dry, to create a silky sauce.
Remove skillet from heat. Drizzle in truffle oil and toss to combine. Sprinkle grated Parmesan cheese and mix gently. Season with salt and pepper to taste.
Plate the tagliatelle and garnish generously with chopped fresh parsley. Serve immediately.