Fill a large pot with water, add 1.5 tablespoons of salt, and bring to a rolling boil over high heat.
Add 12 ounces of tagliolini pasta, stir to prevent sticking, and cook until al dente (2–4 minutes for fresh or 6–8 minutes for dried).
Before draining, reserve 1.5 cups of pasta water, then drain the pasta without rinsing.
Meanwhile, melt 6 tablespoons of unsalted butter in a large skillet over medium heat until it begins to foam.
Optional: add 1 clove garlic (minced) and cook for about 30 seconds until fragrant, without browning.
Add the drained pasta to the skillet, then sprinkle in 1 cup of freshly grated Parmesan cheese, 0.5 teaspoon of freshly ground black pepper, and 0.5 lemon zest (optional).
Toss vigorously, adding the reserved pasta water a little at a time until the sauce emulsifies and coats the pasta.
Serve immediately, garnished with fresh chopped parsley and extra grated Parmesan cheese (optional).