Bring a large pot of salted water to a boil. Cook gnocchi until it floats, 2–3 minutes. Drain, reserving 1/4 cup cooking water.
Heat butter or olive oil in a skillet over medium-high heat. Add gnocchi in a single layer and cook 2–3 minutes until golden, then toss and cook 1–2 minutes more.
Reduce heat to medium. Add garlic and cook 30 seconds until fragrant.
For tomato sauce, add marinara and oregano; simmer 3–4 minutes. For creamy sauce, add heavy cream; simmer 2–3 minutes and stir in extra parmesan.
Add reserved pasta water as needed to loosen the sauce. Stir in parmesan, salt, and pepper.
Garnish with fresh herbs and red pepper flakes. Serve immediately.