Remove and reserve stems from shiitake mushrooms. Thinly slice caps and chill until needed. Place shiitake stems, ginger, coriander seeds, and cloves on a double-thick, 8-inch square of 100% cotton cheesecloth. Bring up corners; tie closed with 100% cotton string.
In a 5- to 6-qt. slow cooker combine spice bag, chicken thighs, water, chicken stock, sliced onion, mushrooms, brown sugar, garlic, and salt. Cover and cook on low 7 to 8 hours or high 3½ to 4 hours. Remove and discard spice bag.
Remove chicken from cooker. Remove meat from bones; discard bones. Coarsely shred chicken using two forks; cover and keep warm. Stir the reserved shiitake caps and noodles into broth mixture. Cover and cook 10 minutes more.
Ladle noodle mixture into shallow bowls. Add shredded chicken and desired toppers.
Tips: If using a sugar substitute we recommend Splenda® Brown Sugar Blend. Follow package directions to use 1 Tbsp. equivalent. Nutrition Facts Per Serving with Substitute: same as below except 243 ca., 26 g carb. (5 g sugars)
To soak rice noodles, in a large bowl combine noodles and enough boiling water to cover. Let stand 3 to 7 minutes or until noodles are tender but still firm (al dente), stirring occasionally.