Preheat the oven to 425. In a sauce pan, melt the butter and brown sugar together and bring to a boil. Allow to boil for about 5-6 minutes - stir occasionally.
Put down parchment or a silpat mat or greased aluminum foil on a rimmed baking sheet. Lay saltine crackers out to cover the baking sheet (the rim part is important).
Pour the brown sugar/butter boiling mixture over the crackers, cover as evenly as possible
Bake at 425 for 4-5 minutes until bubbly.
Remove the sheet pan from the oven and pour the chocolate chips over the crackers. Don’t worry - they will melt. When they melt, use the back of a wooden spoon and spread the chocolate over the crackers. Sprinkle Kosher salt evenly over the surface.
Place the entire baking sheet into the fridge or even the freezer until the chocolate is hard - about an hour. Break it into pieces or cut with a knife or even a pizza cutter to create different sized pieces.
Store in a resealable container and keep in the fridge.