In a pot boil ~3 liters of water and add some salt. When water starts boiling, then add spaghetti and cook for 10-15 minutes until it becomes fully cooked. Strain the spaghetti under cold running water to avoid stickiness.
In a medium sized pan, add 4 tablespoons of oil and add garlic and onion and sauté it for 3-4 minutes. Next add tomatoes and peas and cook for 7-8 minutes or until they become soft. Add red chili powder, salt and cook for 3 minutes. Now add garlic pasta sauce, mix it evenly and add boiled spaghetti, mix again, and turn off the flame.
In a separate pan add remaining 1 tablespoon of oil, heat up for 2 minutes and add brussel sprouts and sauté it for 4 minutes and add salt and black pepper. Cover the pot and let it simmer for 20 minutes.