Arrange tomatoes cut-side up on a baking sheet and sprinkle with minced garlic and salt and pepper to taste. Drizzle with olive oil.
Roast heirloom tomatoes at 375F 25-30 minutes or until tomatoes are very softened. Remove from oven and allow to cool then carefully remove skins and as many seeds as you can. Set aside.
In a large skillet over medium-high heat, melt butter then add gnocchi in a single layer in pan. Sear gnocchi several minutes on each side, turning once until gnocchi is golden-brown. Transfer to a plate and set aside.
In remaining pan drippings, saute onion until very lightly browned. Add red wine (or chicken broth) and saute until liquid is almost evaporated. Add roasted tomatoes to pan, smashing with a wooden spoon to break down tomatoes.
Bring sauce to a low simmer over medium-high heat, continually smashing to break up tomatoes. Reduce heat to medium and add cream, oregano, basil, and seared gnocchi. Season with salt and pepper to taste.
Arrange mozzarella cheese on top and broil gnocchi skillet under high 1-2 minutes until cheese is lightly browned. Serve gnocchi hot and enjoy!