Preheat oven to 200°F. Line a baking sheet with aluminum foil and spray with nonstick spray.

Pour pretzels into a heat-safe bowl.

In a saucepan over medium heat, combine brown sugar, butter, and corn syrup. Bring to a low boil and cook for 5 minutes, stirring constantly.

Remove from heat and stir in vanilla extract and baking soda carefully; the mixture will bubble.

Pour the hot toffee mixture over the pretzels and stir to coat evenly.

Spread pretzels on prepared baking sheet and sprinkle half of the toffee bits over the coated pretzels.

Bake for 1 hour, turning every 15 minutes.

After baking, sprinkle the remaining toffee bits and allow to cool before breaking into pieces.