Preheat oven to 400°F.
Line a sheet pan with parchment paper--we use a jelly roll sized sheet pan, 10 inch by 15 inch.) Arrange the pretzel snaps in 11 rows of 8. The pretzels will shift a bit and that is ok!
Add the brown sugar, butter and sea salt to a saucepan. Melt the butter and sugar together medium/medium-low heat, stirring frequently.
Bring the mixture to a boil and allow it to boil for 3 minutes stirring continuously--it will thicken and turn a nice rich amber color. (If using a candy thermometer, you want 270°F-290°F degrees.) Remove from heat and stir in vanilla extract.
Pour the caramel mixture over the pretzels and spread evenly. If the pretzels shift its ok, you can use a spatula or offset spatula to spread the caramel that will help even them out a bit.
Bake for about 5-6 minutes. The caramel will be vigorously bubbling (300°F-310°F with thermometer).
Remove from the oven and let sit for 2 minutes and then sprinkle the chocolate chips over top evenly. Allow to sit for about 4-5 minutes or until you can easily spread and the chips are melted. If they don't seem to be melted after a bit, pop them in the oven for 1-2 minutes and then spread.
Once the chocolate is spread to cover the caramel, add your favorite toppings. Allow the pretzel toffee to cool at room temperature or in the refrigerator for a few hours.)
Once completely cooled, break the toffee apart or use a sharp knife to cut into small pieces. Enjoy!