Place chicken in a large pot with onions, carrots, celery, and peppercorn; add water to cover. Cover pot and bring to a boil; reduce heat to gentle boil and cook for about 90 minutes or until chicken meat is falling off the bones.
Remove chicken, let cool and shred of chop the meat. Strain broth and discard veggies or save for later use.
Open biscuits. Pinch off pieces and put in bowl of flour. Shake off excess flour and drop into boiling broth a few at a a time. Stir frequently! ** Use as much or as few as you would like!
Once all biscuits are in the broth, lower the heat to medium low, cover and simmer until desired texture of dumpling is achieved. (I like the chewy so I cook them for about 30 minutes.) STIR OFTEN OR THEY WILL STICK!
If you want to thicken the broth, mix a little flour with some water to make a slurry then slowly add to the broth, stiring constantly until well mixes in.
When dumplings are almost done, add chicken back to the pot and stir in the dumplings. Season to taste.