Heat olive oil in a large skillet over medium-high heat for two minutes. Sear chicken breasts on both sides for three minutes each, creating a golden crust that locks in moisture and deepens flavor complexity throughout cooking.
Layer diced onion, minced garlic, sliced carrots, and chopped celery into your slow cooker's base. These aromatic vegetables create the flavor foundation that makes this cozy slow cooker chicken dinner recipe so memorable and delicious.
Place seared chicken breasts on top of the vegetable layer, then add cubed potatoes and sliced mushrooms around them evenly. Pour chicken broth over everything and stir in tomato paste, thyme, rosemary, salt, pepper, and bay leaf gently.
Cover and cook on LOW for 6 hours—this extended time ensures perfectly tender chicken while vegetables become melt-in-your-mouth soft. Resist opening the lid frequently because heat loss disrupts the slow cooking process and extends overall cooking time unnecessarily.
After six hours, remove the bay leaf and carefully shred chicken breasts directly in the slow cooker using two forks. The warm meal should smell absolutely incredible, with vegetables completely tender and broth infused with all the aromatic seasonings.
Gently stir to combine shredded chicken with vegetables and broth, adjusting salt and pepper to your preference. This slow cooker chicken dish is ready to serve immediately for maximum warmth and comfort.