Preheat oven to 425. Line a rimmed cookie sheet with aluminum foil and place crackers in a single layer on the cookie sheet.
In a saucepan over medium heat, bring butter and sugar to a boil and boil for 5 minutes, stirring often.
Remove saucepan from heat and immediately pour caramel over the crackers and spread into an even layer.
Place the pan in the oven and bake for 4-5 minutes, or until caramel is bubbly.
Remove pan from the oven and immediately sprinkle chocolate chips over top. Let the chocolate chips set until they begin to melt, about 2 minutes, then spread into an even layer (an offset spatula works great for this). Sprinkle the top with coarse sea salt.
Let cool completely (you can put the pan into the refrigerator to speed up this process). Break into pieces and store in an airtight container.