Step 1: Prepare the Slow Cooker - Spray an eight quart slow cooker with nonstick cooking spray, making sure to coat the bottom and sides lightly. This little step may not feel exciting, but it helps a lot when the sauce cooks down and gets sticky around the edges. Place the chicken thighs in an even layer in the bottom of the slow cooker. They do not have to be perfect, but try not to pile them too high in one spot so the sauce can reach every piece.
Step 2: Whisk the Apple Cider BBQ Sauce - In a large bowl, whisk together the apple cider, barbecue sauce, brown sugar, Dijon mustard, Worcestershire sauce, apple cider vinegar, minced garlic, smoked paprika, onion powder, salt, and black pepper. Take a minute here and whisk until the brown sugar is mostly dissolved and the sauce looks smooth. This is where all that sweet, smoky, tangy flavor comes together, and mixing it first helps every bite of chicken cook in the same rich sauce.
Step 3: Pour the Sauce Over the Chicken - Pour the sauce evenly over the chicken thighs in the slow cooker. Use a spoon to nudge the chicken around a little if needed so the sauce settles underneath and around each piece. The chicken does not need to be fully submerged, but you want it nicely coated. As it cooks, the chicken will release juices and the sauce will loosen, bubble gently, and wrap around everything.
Step 4: Cook Low Until Tender - Place the lid on the slow cooker and cook on low for 6 to 7 hours, or until the chicken is tender and easy to shred with two forks. I like to check it around the 6 hour mark if I am nearby, but there is no need to hover over it. The chicken is ready when it pulls apart with almost no effort. That is the sign you are headed toward the good stuff, the kind of soft, saucy chicken that makes everyone ask what smells so good.
Step 5: Shred the Chicken - Carefully remove the chicken from the slow cooker and place it on a cutting board or in a large bowl. Use two forks to pull it into tender shreds. If it fights you, it probably needs a little more time, but if it falls apart easily, you are right where you need to be. I like a mix of bigger pieces and smaller shreds because it gives the sandwich a hearty texture instead of turning everything into mush.
Step 6: Return the Chicken to the Sauce - Add the shredded chicken back into the slow cooker and stir it into the sauce until every piece is coated. Put the lid back on and let it cook on low for another 15 to 20 minutes. This last little stretch matters because the shredded chicken drinks in the sauce and gets even more flavorful. It also gives you time to toast buns, slice cheese, set out slaw, or call everyone to the table twice because that is how dinner works in real life.
Step 7: Serve It Warm and Saucy - Serve the pulled chicken warm on brioche buns with coleslaw, cheddar cheese slices, and pickles if you like. The soft bun, juicy chicken, creamy crunch from the slaw, and sharp cheddar all work together in a way that feels like a little backyard barbecue and a cozy fall dinner at the same time. Spoon a little extra sauce over the top before closing the sandwich, then hand out napkins because this is a good messy dinner.