You need:7-8 cups freshly popped corn, preferably from your own popper (no butter!), 6 Tbsp. butter, 3/4 c. brown sugar, 1/2 tsp. baking soda, 1/4 tsp. vanilla, and 3 Tbsp. corn syrup.
Remove the unpopped kernels from your popcorn. Put the corn in a baking or roasting pan and keep warm at a 300 degree oven.
Melt butter, brown sugar, and corn syrup over medium heat until mixture boils, and continue boiling without stirring for 5 minutes.
Remove from heat and stir in soda and vanilla. Pour mixture over warm popcorn.
Bake in 300 degree oven for 15 mins, stir, bake 5 mins more. Spread caramel corn on a large piece of buttered foil or waxed paper to cool.
This lasts a week, but it will be gone before then, guaranteed!