pre-heat oven to 300
line 2 sheet pans with a silicon baking mat or parchment paper or foil
pop all the popcorn and place in two large heat resistant bowls- make sure you seperate any unpopped kernels and remove them, they are not welcome here.
in a really big pot (i'm not making this up, this stuff is going to bubble like the dickens, and you don't want hardened caramel all over your stove.) boil sugar, butter, corn syrup and salt until it reaches 240F (this should take about 5 minutes of constant stirring
remove from heat, add baking soda and vanilla (remember i mentioned bubbling like the dickens? yeah, that's going to happen big time now.) the pepper can be added now, if you like things sweet and spicy.
coat the popcorn with the caramel and mix and stir until all pieces are coated
pour out into the sheet pans and spread into an even layer
bake for 30-35 minutes, you can stir it at 15 minutes to check on it, but nothing crazy bad happens if you don't
remove from the oven, it cools fairly quickly and can be placed in a large bowl to serve, larger clumps should be easy to break apart
add any mix ins you want (like candy corn, pretzels, m&ms...)