Begin by heating 2 tablespoons of olive oil in a large cast-iron skillet over medium-high heat. Season your bone-in, skin-on chicken thighs with salt and pepper. Once the oil is shimmering, sear the chicken thighs skin-side down for about 5-7 minutes until golden brown.

While the chicken is searing, combine 1 cup of ketchup, 1/2 cup of soy sauce, 1/4 cup of honey, 4 minced garlic cloves, 1 teaspoon of onion powder, 1 teaspoon of dried thyme, 1 teaspoon of dried parsley, and 1 teaspoon of dried mustard in a medium bowl. Whisk until smooth.

Transfer the seared chicken, skin-side up, into the slow cooker. Pour the prepared sauce over the chicken, ensuring each piece is well-coated. Cover and cook on HIGH for 3 hours or LOW for 5 hours.

Once cooking is complete, gently remove the chicken from the crock pot and place it on a serving platter. Spoon the savory sauce over the top and garnish with freshly chopped parsley if desired.