POSITION racks in top and bottom thirds of oven, then preheat to 300F. Line 2 baking sheets with parchment.
PLACE popcorn in a large wide bowl. Have pretzels ready.
STIR sugar and water in a large saucepan over medium until sugar dissolves, 2 to 3 min. Increase heat to high and boil, without stirring, until mixture turns amber, 7 to 10 min. Remove from heat and stir in butter and pretzels. Pour over popcorn, stirring with a spatula. Spread in single layer on prepared sheets and sprinkle with gingerbread spice mix.
BAKE in top and bottom thirds of oven, stirring and switching sheets halfway, until popcorn is coated with caramel, 20 min.
Nutrition (per ½ cup)
Kitchen Tip: Microwave or packaged popcorn will work well in this recipe.