To make barbecue sauce: In a small bowl, combine salt, paprika, black pepper, ground cumin, cayenne pepper, rosemary and mustard seed. Mix well and set aside.

In a medium saucepan over medium heat, combine brown sugar, molasses and tomato sauce. Stir until brown sugar has dissolved completely. Add pumpkin purée and pumpkin beer (or chocolate stout) to the saucepan. Stir well to incorporate all ingredients.

Gradually add prepared spice mix and taco seasoning to the saucepan, stirring constantly to ensure even distribution. Reduce heat to low and let the sauce simmer for about 20-30 minutes, stirring occasionally. This allows the flavors to meld together and the sauce to thicken. Taste sauce and adjust the seasoning as needed. If you prefer a sweeter sauce, add a bit more brown sugar or molasses. For more heat, add additional cayenne pepper.

To make chicken: In a small bowl, mix salt, black pepper, paprika, cumin, cayenne pepper (if using), and dried rosemary. Rub this seasoning mixture evenly over the chicken breasts or thighs.

Place onions and garlic at the bottom of the slow cooker. Place seasoned chicken on top of onions and garlic. Pour chicken broth and pumpkin beer (or chocolate stout) around the chicken. Add brown sugar and chipotle chiles to slow cooker. Stir gently to combine. Add just enough water to cover the chicken, about 2 cups.

Cover and cook on low for 6-8 hours, or on high for 3-4 hours, until the chicken is tender and easily shredded with a fork. Once cooked, remove the chicken from the slow cooker and allow to cool. Shred it using two forks. Discard any excess liquid from the slow cooker if desired, leaving just enough to keep the chicken moist.

Smother the chicken with the chipotle pumpkin barbecue sauce. Toast and butter sweet rolls and top with pickles and coleslaw.