Fill a 3-quart pot with water, bring to a boil, and add a dash of salt.
Add the gnocchi to the boiling water and cook over medium heat until they float to the surface, then remove with a slotted spoon to a plate.
In a large skillet, melt 1 tablespoon of the butter over medium heat.
Add the boiled gnocchi in batches and fry until golden and lightly browned on the edges, then transfer to a plate.
Add the remaining 1 tablespoon butter and the olive oil to the skillet and heat until shimmering.
Add the chopped onion and sauté for 2 to 3 minutes until softened.
Add the minced garlic and cook until fragrant and the onion is translucent, about 30–60 seconds.
Stir in the dried oregano and Italian seasoning and cook for 1 minute to bloom the herbs.
Add the crushed tomatoes, stir to combine, and simmer for about 5 minutes.
Add the pan-fried gnocchi to the sauce and toss to coat; simmer briefly so flavors meld.
Season the dish with salt and black pepper to taste, then sprinkle with crushed red pepper flakes, mozzarella, and Parmesan before serving.