Spray the bowl of a slow cooker with cooking spray.
In a large frying pan over medium-high heat, heat olive oil and lay chicken breasts in the pan. Sprinkle with salt and pepper and sear each side of the chicken for 1-2 minutes.
1 tbsp olive oil, 2 lbs chicken breasts, 1/2 tsp salt, 1/4 tsp ground black pepper
Add seared chicken to slow cooker, along with roasted red peppers, olives, and chopped onion.
1 12 oz jar roasted red peppers, 1 cup pitted Greek kalamata olives, 1 red onion
Whisk together remaining ingredients except feta cheese in a small bowl and pour into the slow cooker.
3 tbsp red wine vinegar, 3 cloves garlic, 1 tsp pure honey, 1 tsp dried oregano, 1 tsp dried thyme
Cover and cook on HIGH for 2 hours (or LOW for 4 hours).
Serve and garnish with crumbled feta cheese.
1/2 cup crumbled feta cheese