Trim the chicken of excess skin/fat and pat dry with paper towels. Liberally season the chicken with salt and pepper.
Combine ½ bottle Guinness, ¼ cup molasses and 2 tablespoons oil in a large bowl or zipper-style plastic bag.
Add the chicken and mix to evenly coat the chicken with the marinade. Refrigerate, covered, 6-24 hours.
Refrigerate the remaining ½ bottle of Guinness until ready to use.
When ready to cook the wings, remove the chicken from the fridge and heat the oven to 425°F. Cover a large, rimmed baking sheet with foil and top the tray with a metal cooking rack. Spray the rack with nonstick spray.
Shake any excess marinade off the chicken pieces and evenly space the chicken pieces on the rack. Set the chicken on the middle rack of the oven and bake 30 minutes.
Reduce the oven temperature to 400°F.
In a medium size mixing bowl, whisk together the remaining ½ bottle of beer, ¾ cup molasses, ½ teaspoon salt, ¼ teaspoon ground black pepper, and 1/8 teaspoon crushed red pepper flakes. Reserve half of the glaze for serving.
Remove the chicken from the oven and dip each piece in half of the Guinness/molasses mixture.
Roll and press each chicken piece in the crushed pretzels and set the chicken back on the baking rack.
Bake the chicken an additional 20-30 minutes or until crispy, golden brown and baked throughout. The chicken temperature should register 170°F when tested in the middle of one of the middle pieces of chicken.
Remove the chicken from the oven and serve with the reserved Guinness/Molasses sauce.