Turn on the slow cooker to low while you are preparing the ingredients and let it warm up for about 20 minutes.
Place a large sauté pan over medium heat. Add the extra virgin olive oil until it shimmers and covers the pan easily. Add the thinly sliced onions, sprinkle with the ½ teaspoon of salt, and stir to coat the onions with the olive oil. Stir occasionally for about 10-12 minutes, watching carefully so that the onions do not burn.
Once the onions are finished sautéing, add them along with the chopped apples to the bottom of the pre-heated slow cooker. Salt both sides of the chicken and layer them on top of the onions and apples.
Sprinkle the chicken with the garlic powder. Add the dijon mustard, apple cider, and place on the slow cooker lid. Cook for 4-5 hours on low.
When the chicken is fully cooked, remove it from the slow cooker and shred it with two forks. It should shred easily. Place the shredded chicken back in the crockpot and mix with the juices before serving.
Tip: If there is too much liquid, remove the lid at the end of the cooking time and allow the liquid to evaporate on high for up to an hour.
Core and grate the apple then gently use a clean kitchen or paper towel to remove excess water. Use a medium sized bowl to toss together the four cups of shredded cabbage/carrot mix and grated apples. In a separate small bowl whisk the olive oil, apple cider vinegar, honey, and salt to taste.
Pour the dressing over the coleslaw mix and toss until well combined.
Serve the shredded apple cider chicken on buns topped with the apple coleslaw mix.