Preheat the oven to 350°F (175°C) and line a 10x15 inch jelly roll pan with parchment paper or a silicone baking mat.

Arrange the saltine crackers in a single layer on the prepared pan, ensuring they are tightly packed and touching.

In a medium saucepan over medium-high heat, combine the butter and light brown sugar.

Bring the mixture to a rolling boil and cook for exactly 3 minutes, stirring constantly to prevent burning.

Immediately pour the hot caramel mixture evenly over the crackers and use a spatula to spread it to the edges.

Bake the crackers for 5 to 7 minutes, or until the caramel coating is bubbly across the entire surface.

Remove the pan from the oven and immediately sprinkle the chocolate chips over the hot caramel layer.

Let the chocolate chips sit for 3 minutes until softened, then use an offset spatula to spread them into a smooth, even layer.

Sprinkle the flaky sea salt evenly over the melted chocolate while it is still wet.

Allow the pan to cool to room temperature, then refrigerate for at least 60 minutes until the chocolate is firm before breaking into individual pieces.