Heat olive oil in a skillet over medium heat. Once hot, add the chopped onion and sauté until translucent, about 3-4 minutes. Add minced garlic and cook for another minute until fragrant.
In your slow cooker, place the chicken breasts at the bottom. Season them with salt, black pepper, thyme, onion powder, and garlic powder.
Pour the sautéed onion and garlic mixture over the chicken.
In a separate bowl, whisk together the chicken broth, heavy cream, and Worcestershire sauce. Pour this mixture over the chicken in the slow cooker.
Cover and cook on low for 6-7 hours or on high for 3-4 hours, or until the chicken is fully cooked and tender.
Once cooked, carefully remove the chicken breasts and set them aside. Use two forks to shred the chicken if desired.
In a small bowl, mix the flour with a few tablespoons of the sauce from the slow cooker to make a slurry. Stir until smooth. Pour this slurry back into the slow cooker and stir well to combine. Let it cook on high for an additional 15-20 minutes to thicken.
Return the shredded chicken (if shredded) to the slow cooker and stir well until evenly coated in the sauce.
Taste and adjust seasoning with additional salt and pepper if needed.
Notes
Serve over mashed potatoes or rice, garnished with parsley.