Bring the water to a boil for the spaghetti and season generously with salt. Prepare all of your ingredients. Cut the onions, tomatoes (seeded and chopped), and cheese (grated). In a big pan or wok, warm the olive oil on high. Add the chopped onions when it's boiling. Cook the onions for around 5-8 minutes, stirring constantly. They should begin to brown evenly at this point. Toss in the chopped tomatoes and season with salt. Reduce the temperature to medium-high. Now is the time to add your spaghetti to the saucepan with the water and simmer for 10-11 minutes. Mix the tomato-onion combination often, ensuring nothing burns, for about 5 minutes, or until the tomatoes have broken down. Strain the pasta and drop it into the heated pan with the tomatoes and onions as soon as possible. Increase the heat to high. To fully mix and cover the spaghetti with the tomatoes and onions sauce, use spaghetti tongs. Add a third of the cheddar and stir thoroughly with tongs once more. Allow it to rest for two minutes without mixing to crisp up the bottom parts. Pour in the remaining third of the cheese and set aside for two minutes without mixing. Repeat with the last third of the shredded cheddar. Test if it's crunchy enough to your preference after the last two minutes of grilling. If you want it crispier, stir the spaghetti once more and set it aside until it's crispy enough for you. Add salt to taste with salt and pepper. Enjoy!