Dice the potatoes, slice the carrots and celery, chop the onion, and mince the garlic. Trim any excess fat from the chicken and cut into large chunks if using thighs.
Layer the Crock Pot starting with potatoes at the bottom, followed by carrots, celery, onion, and garlic. Place the chicken on top.
In a bowl, whisk together chicken broth, tomato paste, thyme, rosemary, salt, and pepper. Pour this over the chicken and veggies.
Nestle bay leaves into the broth mixture.
Cover and cook on low for 6-8 hours or high for 3-4 hours until the chicken is tender and veggies are soft but not mushy.
About 30 minutes before serving, stir in frozen peas if using. Remove bay leaves before serving.
