Fill a large pot with salted water and bring it to a boil. Add the tagliatelle pasta and cook according to package instructions until al dente, usually around 7–9 minutes. Stir occasionally to prevent sticking. Once cooked, reserve about 1/2 cup of the pasta water, then drain the pasta and set aside.
While the pasta is cooking, heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the peeled and deveined shrimp, seasoning lightly with salt and pepper. Cook for 2–3 minutes on each side until they turn pink and opaque. Remove the shrimp from the skillet and set aside to avoid overcooking.
In the same skillet, add the remaining tablespoon of olive oil. Toss in the sliced mushrooms and sauté for about 5 minutes until they release their moisture and turn golden brown. Add the minced garlic and cook for an additional minute until fragrant, stirring frequently to avoid burning.
Lower the heat to medium and pour in the heavy cream, stirring to combine with the mushrooms and garlic. Let the cream simmer gently for 2–3 minutes to thicken slightly. Add the lemon juice, then season with salt and pepper to taste. If the sauce looks too thick, add a splash of the reserved pasta water to reach your desired consistency.
Add the cooked tagliatelle to the skillet, tossing to coat the pasta evenly in the creamy mushroom sauce. Return the shrimp to the pan and gently mix everything together for another minute to heat through.
Remove from heat and sprinkle freshly chopped parsley over the top. Serve immediately for the best flavor and texture. This dish pairs wonderfully with a crisp green salad or steamed vegetables for a complete meal.