Oil. In a 10" diameter cast-iron skillet or other oven safe pan, heat olive oil over medium heat. Add onions to the skillet and cook until tender. Stir occasionally. About 5 minutes. The onions will have a yellow color.
2 Tablespoons olive oil
Saute. To the cooked onions, add the pressed garlic, marsala, and sugar. Continue to cook for approximately 5 minutes more. The onions will have a brownish color and should become more translucent.
1/4 cup Marsala (optional), beef broth or water as substitute, 2 teaspoons granulated sugar
Sauce. To the cooked onions, add the diced tomatoes and juices, salt, and pepper. Increase heat to medium high and simmer the sauce for about 15 minutes. Stir occasionally. The tomato juices will reduce completely.
28 oz diced canned tomatoes, 1 teaspoon sea salt + 1 teaspoon per 3 cups of water to cook pasta, 1/8 teaspoon ground black pepper
Pasta. While the tomato sauce is cooking. Bring salted water to a boil for the pasta. I recommend 1 teaspoon of salt for every 3 cups of water. I also like to break the fettuccine in half before cooking. I think it fits better in the pan and it's easier to manage when eating. Cook the pasta per the directions on the box. Remember to reserve at least 1/4 cup paster water before draining.
12 oz dried fettuccine pasta
Simmer. After getting the pasta going and the tomatoes have cooked for roughly 15 minutes the tomatoes should become softer and the juices will reduce. Then, slowly add in the beef broth 1/2 cup at a time to keep the temperature from dropping too much. Bring the sauce back to a simmer and cook for 10 minutes.Take this time to measure the cream, ricotta, and mozzarella. 1 1/2 cups beef broth (or make broth from paste)