Bring a large pot of salted water to a boil—about a tablespoon of salt per 4 liters of water. Add the pasta and cook until al dente. Drain, reserving about half a cup of the pasta water for later.
In a large pan, heat the olive oil over medium heat. Add the minced garlic and cook until fragrant—about 30 seconds. Stir in the pesto and half the Parmesan. If it feels thick, add a few tablespoons of reserved pasta water to loosen it.
Add the drained pasta to the pan with the pesto sauce. Toss in the cherry tomatoes and peas, stirring well so everything is coated. Add more pasta water as needed for a silky consistency. Sprinkle in the remaining Parmesan and nuts if using. Season with salt and pepper.
Transfer to bowls or a large serving platter while still hot. Garnish with fresh basil leaves and a dusting of Parmesan for that beautiful festive look.