Spinach Tortellini Soup

This is SOOO good--probably my favorite soup, especially when I'm sick. There's no meat, which is nice because I don't have to thaw it out first.

10 oz. package of frozen chopped spinach
1 med. onion
2 cloves garlic
1 quart chicken broth
14 oz. can diced tomatoes
2 cups frozen cheese tortellini
3 Tbsp. parmesan cheese
1 egg
salt and pepper to taste

Throw the spinach in the microwave and microwave it on high for 3-4 minutes until thawed. While that's thawing, heat a soup pot over medium heat and spray with cooking spray. Chop and add onion and garlic. Cook until soft. Add chicken broth and 2 cups water. Bring to a boil. When the spinach is done thawing, put it in a clean towel, and squeeze out all the liquid by wringing the towel out. Add the spinach to the pot, as well as the tomatoes. Bring back to a boil. Add the tortellini. In a small bowl, beat the egg and and the cheese, salt and pepper to the egg, combining it all together. When the tortellini is done cooking (just takes a couple minutes), stir and slowly drizzle the egg mixture into it. Keep stirring so that the egg doesn't scramble.