If using whole chicken breasts/thighs, cut them into 1-inch pieces. Heat olive oil in a large skillet over medium-high heat. Add chicken and cook until lightly browned on all sides (it doesn't need to be cooked through). This step is optional but adds depth of flavor. Transfer the browned chicken (if using) or raw chicken pieces directly into the 6-quart slow cooker. Add chopped onion, diced carrots, and diced celery.

Pour in the chicken broth, cream of chicken soup, and heavy cream (or milk). Stir well to combine. Add dried thyme, black pepper, and salt. Stir again to ensure everything is evenly distributed.

Cover the slow cooker and cook on LOW for 6-7 hours, or on HIGH for 3-4 hours, until the chicken is very tender and the vegetables are soft.

About 30-45 minutes before the end of the cooking time for the chicken base, prepare the dumplings. In a large mixing bowl, whisk together the flour, baking powder, and salt.

Add the cold, cubed butter to the flour mixture. Using a pastry blender, two knives, or your fingertips, cut the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.

Gradually add the milk, stirring with a fork until a shaggy dough forms. Do not overmix. The dough should be moist but not sticky.

Stir in the frozen peas into the chicken stew. Then, drop the dumpling dough by the spoonful (about 1-2 tablespoons each) directly onto the hot chicken stew in the slow cooker. You can lightly flatten them or leave them as irregular drops. Arrange them so they are mostly sitting on top of the liquid.

Cover the slow cooker again and continue to cook on HIGH for another 20-30 minutes, or until the dumplings are cooked through, fluffy, and have expanded. They should be firm to the touch when gently pressed.

Ladle the hearty chicken and dumplings into bowls. Garnish with fresh parsley if desired. Serve hot and enjoy!