Preheat oven to 200°F. Line a baking sheet with heavy-duty aluminum foil and generously spray with nonstick cooking spray.

Pour pretzels into an extra-large heat-safe bowl.

In a 3 to 4-quart saucepan over medium heat, combine light brown sugar, sliced butter pats, and light corn syrup. Bring to a low boil, stirring constantly, and boil for 5 minutes.

Remove from heat and carefully stir in vanilla extract and baking soda. The mixture will bubble up and thicken quickly.

Immediately pour the hot toffee over the pretzels. Carefully stir to coat evenly with a wooden spoon or silicone spatula.

Spread the coated pretzels onto the prepared baking sheet. Sprinkle half of the Heath toffee bits over the top.

Bake for 1 hour, turning pretzels at 15-minute intervals to ensure even coating.

As soon as baked, sprinkle remaining toffee bits over the pretzels and let cool completely before breaking into pieces.