Bring a large pot of salted water to a boil over high heat. Add the pasta and cook until just under al dente, about 10 or 11 minutes. Save and set aside the pasta water.
Meanwhile heat a large straight sided skillet over medium heat. Add the butter to the hot pan. When the butter is melted add the garlic and cook, stirring often until soft and fragrant. Add 1/2 cup of the pasta water and reduce the heat to low.
When the pasta is ready remove it from the water and add it directly to the pan with the sauce. Bring the heat back to medium and sprinkle 1 1/2 cups of the parmesan directly on the plain pasta. Stir to combine.
Add the mascarpone, zest and salt. Toss well to coat adding pasta water as needed to thin the sauce and to assist in finishing cooking the pasta.
Add the peas, lemon juice and remaining cheese. Toss well to combine adding pasta water as needed to reach the desired consistency of the sauce. You will more than likely use close to 1 1/2 cups pasta water total.
Sprinkle with the pink peppercorns and additional parmesan if desired.