Dress the Bowl: Add 2 to 3 tablespoons of dressing to a large salad bowl, creating a light coating at the bottom before adding the greens.
Toss the Arugula: Add the washed, dried arugula and gently toss it with salad tongs, scooping upward from the bottom so the leaves are lightly coated without becoming heavily dressed.
Add the Mushrooms: Add the cleaned, thinly sliced button mushrooms and gently toss again to distribute them throughout the dressed arugula.
Finish the Salad: Scatter the shaved Parmesan and toasted pine nuts evenly over the top of the salad.
Adjust the Dressing: If the salad needs additional dressing, gently move the salad toward one side of the bowl. Add another 1 to 2 tablespoons of dressing to the exposed bottom of the bowl, then repeat the gentle tossing technique from the first step. Season to Taste: Add a little more salt and freshly ground black pepper according to your preference, taking the Parmesan's saltiness into account.
Serve Fresh: Serve the salad immediately for the best texture, allowing the crisp arugula, tender mushrooms, Parmesan, and toasted pine nuts to come together while fresh.