Bring a large pot of salted water to a boil. Once boiling, add the potato gnocchi. Cook according to package instructions, usually about 2-3 minutes, or until they float to the surface. Drain the gnocchi in a colander and set aside.
In a large skillet, heat 1 tablespoon of olive oil and 1 tablespoon of butter over medium heat. Once melted and shimmering, add the chopped onion. Sauté for about 3-4 minutes until the onion becomes translucent. Then, stir in the minced garlic, dried oregano, and Italian seasoning. Cook for an additional 1-2 minutes until fragrant.
Pour in the crushed tomatoes, followed by the salt, black pepper, and crushed red pepper flakes if using. Stir everything together and let the sauce simmer for about 10 minutes, allowing the flavors to meld beautifully.
Add the cooked gnocchi to the skillet with the tomato sauce. Gently toss to coat the gnocchi in the sauce, ensuring each piece is generously covered. If the sauce seems too thick, you can add a splash of pasta water to loosen it up.
Remove the skillet from heat and sprinkle the shredded mozzarella and grated Parmesan cheese over the top. Place a lid on the skillet and let the residual heat melt the cheese for about 2-3 minutes.
Once the cheese is melted and bubbly, give the gnocchi a gentle stir. Serve hot, garnished with extra Parmesan or fresh basil if desired. Enjoy your delicious gnocchi with tomato sauce!
