Place popped popcorn on baking sheet in 300 degree oven while making caramel mixture.
In a medium saucepan combine brown sugar, butter, and corn syrup. Cook and stir over medium heat until boiling.
Continue to boil for 5 minutes without stirring.
Remove saucepan from heat; stir in vanilla and baking soda.
Pour caramel mixture over popcorn; gently stir to coat.
Bake in 300 degree oven for 15 minutes. Stir mixture and bake for additional 5 minutes.
Spread caramel corn on a large piece of buttered foil to cool. Meanwhile melt chocolate chips over double boiler.
Drizzle caramel popcorn with melted chocolate and Twix bites. Allow chocolate to set before serving.