Melt butter in a saucepan. Add onion and garlic; cook till onion is soft. Add chicken strips and cook 2-3 minutes or till no longer pink. Add stock, water, spinach and pasta. Cover, increase heat to high and bring to a boil. Reduce heat; simmer covered 5-7 minutes till chicken and pasta are cooked.
Meanwhile, whisk together eggs and both peppers.
Bring soup back to a boil and add egg mixture in a slow steady stream, using a back and forth motion. Remove from heat as soon as egg has set. Pour into 4 bowls, sprinkle each serving with cheese.