On a half-size commercial sheet pan, line with parchment. (A little cooking spray will help it stay in place)
Preheat oven to 350˚.
Spread pretzel sticks in a single layer evenly over the entire pan.
In a medium saucepan combine butter and brown sugar over low heat. Allow butter to melt and stir to combine.
Increase heat to medium and bring to a boil for 1 minute, stirring constantly.
Remove from heat and add vanilla.
Immediately pour over pretzels and spread evenly. It may start to solidify quickly.
Place in preheated oven and bake until toffee starts to bubble evenly.
Remove from oven and sprinkle chocolate chips on top.
Place back in the oven for 1 minute.
Remove and using a spatula, spread melted chocolate chips on top of toffee.
Add any toppings and allow to cool completely.