Season the chicken thighs generously with salt and black pepper. In a skillet over medium heat, brown the chicken for about 3-4 minutes on each side until it’s beautifully golden brown.

Place the browned chicken into the slow cooker. Top it with the diced green and red bell peppers, yellow onion, sliced mushrooms, and minced garlic for that aromatic kick.

In a separate bowl, whisk together the tomato sauce, canned diced tomatoes (with juice), chicken stock, Italian seasoning, and red pepper flakes. Pour this vibrant mixture over the chicken and veggies in the slow cooker.

Cover the slow cooker and set it to cook on high for 3-4 hours or low for 7-8 hours, until the chicken is tender and fully cooked through.

Once cooked, carefully remove the chicken from the slow cooker. Stir in your choice of Kalamata olives or capers into the sauce, then mix it well for added flavor.

For an extra touch, broil the chicken in the oven for about 5 minutes to achieve crispy skin before serving.