Place the beer, pumpkin puree, and brown sugar in a large bowl, and heat in the microwave in 15 second increments, until very warm (but not hot).
Stir together, then sprinkle the yeast on top and set aside for 5 minutes, or until the yeast has fully dissolved.
Add the oil and salt, and stir in 4 cups of flour. Mix until the dough forms a ball and pulls away from the sides of the bowl cleanly. (If the dough is too sticky, add up to 1/4 cup of additional flour.)
Allow the dough to rise (covered) for 45 minutes.
Line baking sheets with parchment paper, and lightly mist with non-stick spray.
Divide the dough into 12 equal portions, and roll each into a rope about 18-inches long.
Twist into a pretzel shape, and place on the prepared pans.
Allow to rise for 25 minutes.
Fill a large pot with water and bring to a low boil.
Add baking soda, and boil the pretzels for about 30 seconds on each side. Drain on clean towels.
Preheat the oven to 450 degrees F, and transfer the pretzels to parchment-lined baking sheets.
Bake for 10-12 minutes, or until deep golden brown and puffy.
Cool the pretzels completely.
Stir the sugar, pumpkin pie spice and salt together in a small bowl.
Brush the pretzels lightly with melted butter, then coat with the Pumpkin Spice Sugar.