Preheat the oven to 350F. Line a rimmed baking sheet with parchment, foil or a silicone mat to prevent clean-up after (and to make it easier to get the crack out); line with saltine crackers, placing them right together. I wind up with six rows of 8 crackers.
In a medium saucepan, bring the butter and brown sugar to a boil over medium-high heat, stirring until it goes from looking separated to a more uniform caramel. Let it bubble for 3 minutes, then remove from the heat and pour it evenly over the crackers. Spread it with a knife to fill any gaps.
Place in the oven and bake for 10-12 minutes, until it's deep golden. Keep an eye on it for the last few minutes to make sure it doesn't burn.
Remove from the oven, let cool for a few minutes and then scatter chocolate chips over top, while the caramel is still very warm. Let sit for a few minutes, then spread evenly with a knife.
Cool completely on the countertop or in the fridge, then bash into pieces.
Serving Size Makes lots (but never enough).