Preheat oven to 225 degrees
Put popcorn in a pan large enough to allow the popcorn to be stirred together with the topping.
Combine butter, brown sugar, salt and corn syrup in a medium-size saucepan.
Stir frequently over medium heat until mixture comes to a full boil. Continue to stir and cook for 5 more minutes.
Remove from heat and add the baking soda and vanilla, stirring well.
Pour mixture over the popcorn and stir well to coat popcorn.
Bake for approx. an hour or until popcorn is crunchy, stirring popcorn at 15-minute intervals.
Spread popcorn out onto parchment paper and allow to cool completely.
Heat chocolate chips in the microwave for 30 seconds at a time, stirring after each 30 seconds until chips are melted. Drizzle melted chocolate over popcorn. Sprinkle with toffee chips. Allow chocolate to firm up before storing.
Store in an airtight container.