Lightly coat a large (the biggest you have - or if you don't have really large mixing bowls, you'll have to use two and divide popcorn in half), mixing bowl with non-stick cooking spray. Add popped popcorn and set aside.
Line two 15x10" baking pans with parchment paper and lightly spray with non-stick cooking spray. Set aside. Preheat oven to 250 F degrees.
Add brown sugar, butter, corn syrup, molasses, ginger, cinnamon and salt to a heavy bottomed saucepan and heat over MED heat, stirring constantly. Bring to a boil, then boil without stirring for 4 minutes.
Remove from heat and stir in baking soda and vanilla. The caramel will foam a little bit, that's okay. Working quickly, pour mixture over popcorn and mix as well as you can. If not all the popcorn is covered, that's okay, as it bakes the caramel will thin out and be easier to stir and coat.
Transfer popcorn to prepared baking pans. Bake for 1 hour, stirring every 10-15 minutes. Let cool in pans, break apart any large clumps and store in an airtight container.