Persian Spinach and Yogurt Dip (Borani Esfanaj)

1. 2 quarts water
2. 1 (10-ounce) package fresh spinach, chopped
3. 2 teaspoons butter
4. 1/3 cup finely chopped sweet onion
5. 1 garlic clove, minced
6. 1/2 teaspoon salt
7. 1 cup plain fat-free organic yogurt (such as Stonyfield Farm)
8. 1/4 teaspoon freshly ground black pepper
9. 1/8 teaspoon ground cinnamon

Bring 2 quarts water to a boil in a Dutch oven. Add fresh spinach, and cook for 1 minute. Drain well. Place spinach on several layers of paper towels; squeeze until barely moist. Melt butter in a medium nonstick skillet over medium heat. Add onion and garlic; cook 6 minutes or until onion is tender, stirring occasionally. Remove from heat; stir in spinach and salt. Cool to room temperature. Combine spinach mixture, organic yogurt, black pepper, and ground cinnamon in a medium bowl. Let stand for 30 minutes. Refrigerate until chilled.