1 Preheat the oven to 400F. Line a 10×15-inch jelly roll pan with nonstick aluminum foil (preferred) or regular heavy duty foil, making sure that the foil completely covers the bottom and sides of the pan. If using regular foil, spray lightly with baking spray. Line the saltine crackers in a single layer on the bottom.
2 Make the caramel sauce: Place the brown sugar, butter and salt in a medium sized saucepan. Cook on medium heat, stirring frequently, until the butter melts. Continue to cook, stirring occasionally, for another 3 to 5 minutes, just until the mixture comes to a boil and starts to darken. Remove from heat and stir in the vanilla extract.
(Note: You’re not actually making true caramel here, so you don’t need to be as precise or worry about the temperature of the caramel. Just make sure it comes to a boil and wait for it to darken slightly, then continue.)