Bring a large pot of salted water to a boil. Cook gnocchi according to package instructions. Drain, but reserve 1 cup of cooking liquid.
Meanwhile, warm butter in a large skillet over medium heat. Once melted, toss in cooked gnocchi. Let cook for 1 minute, then take off the heat. Stir in pesto, tossing to coat. Season to taste with salt.
To serve, spoon some gnocchi in a shallow bowl and top with freshly grated Parmesan and black pepper. If you’d like to level up the dish, top with some baby arugula leaves, toasted walnuts and a squeeze of lemon juice.