Preheat oven to 350 degrees. Line a large baking sheet (with sides) with parchment paper or non-stick aluminum foil. Place saltine crackers evenly on the tray (you will want them as close together as possible).
In a medium saucepan, bring butter and brown sugar to a boil, whisking constantly. Once boiling, reduce the heat to med-low and allow to cook for 3 minutes, stirring constantly. Pull off of the heat and pour evenly over the saltine crackers (the hot liquid might make the crackers move around on the baking sheet; if that happens, it's fine).
Bake for 5 minutes, or until the liquid is bubbly. Pull out of the oven and allow to cool.
In the microwave in 30-second increments, melt chocolate chips, stirring after each hit in the microwave. Once the chips are melted, pour over the toffee and spread with a spatula. Sprinkle with Heath Bar Toffee bits.
Allow the toffee to cool before breaking or cutting into pieces (it takes about 3 hours cooling on the counter and about 1 hour in the fridge).
Enjoy!