Begin by cutting the chicken into 1-2" chunks. Then add the chicken, chopped onion, minced garlic, and sliced mushrooms to your slow cooker.
In a separate bowl, whisk together the chicken broth, Worcestershire sauce, thyme, and paprika. Pour the mixture over the chicken and vegetables in the slow cooker.
Cover the slow cooker and cook on low heat for 6-8 hours, or on high heat for 3-4 hours.
After the cooking time is up, remove the lid from the slow cooker and stir in the sour cream. Season with salt and pepper to taste.
Instant Pot Instructions
Set your Instant Pot to sauté mode and heat the olive oil. Add the onion, garlic, and mushrooms to the Instant Pot and sauté until softened, about 3-5 minutes.
Add the thyme, paprika, salt, and black pepper to the Instant Pot and stir to combine.
Pour in the chicken broth and add the diced chicken to the pot. Stir everything together.
Close the Instant Pot and set it to manual high pressure for 5 minutes. Once the cooking time is up, allow for a natural release for 10 minutes, and then manually release all remaining pressure.
Remove the lid and switch the Pot to sauté. Add the sour cream mixture to the Instant Pot and stir to combine. Cook for a few minutes until the sauce thickens.