Cover a rimmed baking sheet with foil and spread crackers on it in a single layer.

Preheat the oven to 400.

Combine butter and sugar in a small saucepan and boil for 3 minutes. Pour this mixture over the crackers. (It's a bit thick; I spread it around with a silicone spatula.)

Put the whole thing in the oven for about 5 minutes. Remove from the oven and sprinkle with chocolate chips. (I found that it helped if I let it sit for about a minute first, to solidify just enough that I didn't displace the syrup when I added the chocolate.)

Let sit for 5 minutes (so the chocolate can melt), then spread the chocolate evenly with a spatula.

Let cool completely. (This takes ages. Like...hours and hours. I finally gave up and popped it in the freezer for about 20 minutes.) Break into pieces.