Cut white parts of onions into 1/2-inch pieces. Heat a large saucepan over medium-high heat; add oil to pan and swirl to coat. Add white parts of green onions and half of the sliced mushrooms. Cook 3 minutes, stirring occasionally. Add stock, garlic, anise and ginger to the pan and bring to a boil. Boil 5 minutes.

Add chicken to pan and reduce heat; simmer for 6 minutes or until chicken is done. Remove from heat.

Prepare noodles according to directions. Cut green parts of onions into 2-inch sections. Add onions, cooked noodles, salt, pepper and remaining 2 oz mushroom caps to the soup. Remove star anise pods and ladle into bowls.