Pop your popcorn according to directions. Be sure and check for any UN-popped kernels, those are the WORST to bite into unexpectedly.
Place popcorn and chopped pecans in a large bowl and set aside.
Combine brown sugar and cinnamon, butter and karo in a medium sized pan and cook over medium heat, stirring constantly, until the mixture comes to rolling boil. Remove from heat and add your vanilla and baking soda. The baking soda will make your caramel mixture foam up and rise, don't be alarmed, it's suppose to (this is why you need to use a tall sided pot if you have one).
Pour your caramel mixture over your popcorn and pecans and stir well.
Spread popcorn mixture onto a foil-lined cookie sheet. Place in oven and bake for 30 minutes. Stir every 10 minutes.
Remove from oven and let cool down. Break into bite size pieces. Melt white chocolate in microwave or stove top, then drizzle over popcorn.
Eat and Enjoy. Store remaining popcorn in an air tight container.