01 - Sprinkle salt and pepper evenly over both sides of the chicken thighs to prepare them for cooking.
02 - Heat a large skillet over medium-high heat. Sear the seasoned chicken thighs for 2-3 minutes per side until lightly browned. This optional step enhances the depth of flavor in the final dish.
03 - Arrange the sliced onions, bell peppers, mushrooms, and minced garlic in an even layer at the bottom of the slow cooker insert.
04 - Place the browned chicken thighs directly on top of the vegetable layer, ensuring they are not overcrowded.
05 - Pour in both cans of tomatoes, white wine or broth, and add the oregano, basil, thyme, salt, black pepper, and red pepper flakes. Stir gently to distribute the seasonings throughout the liquid.
06 - Scatter the drained capers and sliced black olives evenly across the top of the mixture.
07 - Cover with the lid and cook on LOW setting for 6 hours or HIGH setting for 3 hours. The chicken is done when it reaches an internal temperature of 165°F and easily pulls away from the bone.
08 - Taste the sauce and add additional salt or pepper if needed to balance the flavors.
09 - Sprinkle chopped fresh parsley over the finished dish. Serve hot, offering grated Parmesan cheese on the side. Pairs well with crusty bread, creamy polenta, or your favorite pasta.