Bring water to a boil in a large sauce pan. Add spaghetti noodles and cook for 8 minutes. While noodles are cooking, sauté mushrooms and garlic in 1 tablespoon olive oil until mushrooms are tender. Drain noodles and return to sauce pan. Add remaining olive oil and marinara sauce and cook for 1 more minute until sauce is warmed through, stirring occasionally. Transfer spaghetti into individual bowls and top with mushroom mixture and torn basil.