Line a baking sheet with parchment paper and line up the saltine crackers in rows.
Melt the butter and brown sugar in a sauce pan and bring the mixture to a boil.
Boil the mixture for 2 - 3 minutes, stirring constantly, until thick.
Pour the thickened toffee over the saltines and spread it out evenly using a rubber spoon or spatula.
Bake the toffee covered saltines at 350 degrees for 4 - 5 minutes, until browned and bubbly on top.
Remove the pan from the oven and sprinkle the chocolate chips over the top.
After the chocolate sits for 5 minutes and is mostly melted, use the back of a spoon to spread it evenly across the crackers.
If you are adding other toppings like crushed candies, chopped nuts, m&m's, chopped heath bits, etc, add them now while the chocolate is melted.
Place the Christmas crack in the fridge or freezer until set, then break into pieces.
Store leftovers in the fridge or freezer in an airtight container or bag.