In a large pot of salted boiling water add pearl onions whole and cook until tender, 5-8 minutes. Drain and let cool. Trim the root ends and peel, the onions should pop right out of the skins.
In a braising pot or dutch oven heat olive oil over medium heat. Add pancetta to pot and cook, stirring occasionally, until fat is rendered and pancetta is brown 8-10 minutes. Using a slotted spoon, transfer pancetta to a large bowl.
Add onions to same pot and cook, stirring occasionally, until beginning to brown, 8-10 minutes. Add garlic and stir frequently until the aroma is released about 1-2 minutes. Transfer onions and garlic to bowl with pancetta.
Pat dry the chicken and season with salt and pepper. Depending on the size of your pot(or if you’re cooking 5lbs of chicken) you may need to work in batches to avoid any overlapping. Add chicken to pot skin side down and cook, turning, until browned on all sides, about 10-15 minutes per batch; transfer to bowl with onions.
Carefully drain fat from pot and bring to medium-high heat. Add red wine vinegar and MiaBella balsamic to pot and bring to a boil. Scrap up any browned bits from the bottom of the pot and stir to incorporate. Add chicken stock, dried cranberries, bay leaves, and the reserved chicken, pancetta, onions, and garlic to pot. Bring to a boil, reduce the heat, and simmer, partially covered, until chicken is fork-tender, 35-40 minutes.
Using a slotted spoon, transfer chicken and onions to a large platter for serving. Remove bay leaves and spoon sauce over chicken and onions.
You can also prepare up to this step ahead of time and bring the dish back up to temperature over a low flame before serving.