First, bring a large pot of generously salted water to a rolling boil. Add the potato gnocchi and cook for about 3-4 minutes. You'll know they're done when the little pillows float to the surface. Before draining, be sure to reserve about a half cup of the starchy pasta water for the sauce later.
While the gnocchi is cooking, heat the olive oil or butter in a large oven-safe skillet over medium heat. Add the minced garlic and cook for about one minute until it becomes fragrant. Be careful not to let it burn, as that can make the sauce taste bitter.
Pour the marinara sauce into the skillet with the garlic. Stir in the chopped fresh basil and the grated Parmesan cheese. Allow the mixture to come to a gentle simmer, stirring occasionally to combine all the flavors.
Turn off the heat and slowly stir in the heavy cream. Add the cooked gnocchi and the reserved pasta water to the skillet. Mix everything together until the cream is fully incorporated and the gnocchi are evenly coated in the beautiful, glossy sauce.
Top the gnocchi evenly wit a close eye on it until the cheese is completely melted, bubbly, and just beginning to turn golden brown in spots. Serve immediately while it's hot and cheesy.