Sauté the Aromatics: Heat the olive oil in a medium saucepan over medium heat. Add the finely chopped onion and cook for 5-7 minutes, until softened and translucent. Add the minced garlic and cook for another minute until fragrant.

Build the Sauce: Pour the tomato passata and ketchup into the saucepan with the onions and garlic. Stir in the apple cider vinegar, dark brown sugar, Worcestershire sauce, smoked paprika, mustard powder, salt, pepper, and cayenne pepper (if using).

Simmer the Sauce: Bring the sauce to a gentle simmer and cook for 5 minutes, stirring occasionally, to allow the flavours to meld together. Then, remove from the heat.

Prepare the Crockpot: Place the chicken thighs in the bottom of your slow cooker pot in a single layer. Pour the prepared barbecue sauce evenly over the chicken, ensuring it's all coated.

Slow Cook: Cover the crockpot and cook on the 'Low' setting for 6-8 hours or on the 'High' setting for 3-4 hours. The chicken is done when it is cooked through and very tender. I find that the low setting yields the most succulent results.

Shred the Chicken: Once cooked, use two forks to shred the chicken directly in the slow cooker. What works best for me is to do it right in the pot, as this allows the shredded meat to soak up even more of that delicious sauce. Stir everything together until the chicken is fully coated.

Serve: Let the shredded chicken sit in the warm sauce for another 10-15 minutes to absorb the flavour. Serve warm on brioche buns, with jacket potatoes, or your favourite sides.