Pat chicken breasts dry with paper towels.

In a skillet over medium heat, sauté the diced onion and minced garlic for about 5 minutes until they become fragrant and translucent.

In a small bowl, mix the smoked paprika, cayenne pepper, salt, and pepper. Rub this spice blend on both sides of the chicken breasts.

Place the seasoned chicken in the slow cooker. Top with sautéed onions and garlic, then pour barbecue sauce over everything.

Cover the slow cooker and set to low for 6-8 hours or high for 3-4 hours until the chicken is tender.

Shred the chicken right inside the slow cooker using two forks and mix with the sauce to coat.