Line a 10x15-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. Place the saltine crackers in a single layer on the bottom.

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 often, for another 3 to 5 minutes, until the mixture comes to a boil and in color and sugar melts and emulsifies with the butter into a smooth sauce. Do not allow the mixture to boil longer than 30 seconds. Remove from heat and stir in the vanilla extract.

Spread to evenly coat the crackers.

Bake for 5 minutes. The caramel will be hot and bubbly throughout.

Place the chocolate in a microwave-safe bowl. Cook it in the microwave in 30-second intervals at full power, stirring each time, until the chocolate has fully melted (about 1 ½ minutes total).

Once the crackers are done baking, remove from the oven and allow to cool for 1 minute exactly, until the caramel is no longer bubbling and the crackers settle back into place. Then pour the melted chocolate over the crackers. Use a spatula to spread the chocolate evenly over the top.

Let the crackers cool to room temperature then move to the refrigerator and chill overnight.

The crackers will form a single sheet once cool. Remove from pan and gently peel the foil away, being careful not to tear the foil. Cut the candy into snack-sized pieces using a chefs knife.