Poor Mans Toffee-Saltines never tasted this good

I have actually heard this called many things, but I got this recipe from my mother-in-law and her recipe called it this.
Poor Mans Toffee 
1 cup unsalted butter (must use butter!)
1 cup brown sugar
2 cups semi-sweet chocolate chips
40 saltine crackers

Preheat oven to 350ºF. Line cookie sheet with foil and spray with non-stick spray. Lay a flat layer of crackers out on the foil. Melt the sugar and butter until a boil is reached. Reduce the heat and simmer, uncovered, for 5-6 minutes or until mixture is thickened and sugar is completely dissolved. Pour this mixture over the crackers and spread to coat evenly. Bake for 8-10 minutes, or until the toffee becomes bubbly. After removing the pan from the oven, let it sit for 3-5 minutes. Sprinkle on the chocolate chips, let them soften and melt, and then spread them into an even layer. Let cool and refrigerate until hardened. Break into pieces the size of your choice.