Poke holes into bratwurst sausage and place in a plastic bag. Add 1 bottle of gluten free beer and let soak for 1 hour or overnight in the refrigerator.
Lightly spray a 2qt casserole dish and set aside. Preheat oven to 350°F (176° C).
In a medium skillet, cook bratwurst and beer over medium heat. Continue to cook until beer reduces in half. Skim fat off of surface during cooking process. Remove from heat and drain remainder of beer into prepared casserole dish. Set aside. Return sausage back to heat and continue to cook over medium heat until golden brown. Add sauerkraut to sausage and continue to cook for 10 minutes. Remove from heat and add to remainder of beer in casserole dish. Cook at 350°F covered for 30 minutes.
Slice each Kinnikinnick Hot Dog Bun ¾ of the way across the top of the bun lengthwise. Brush the inside of each bun with mustard (optional). Place cooked sausage in prepared bun and top with prepared sauerkraut. Garnish with pickled peppers if desired. Serve immediately. Yields 4