Preheat your oven to 400°F (200°C).
Line your baking sheet with aluminum foil or parchment paper for easy cleanup.
Arrange the saltine crackers in a single layer on the baking sheet, covering the entire surface.
In a medium saucepan over medium heat, melt the butter. Once melted, add the brown sugar, whisking continuously until the mixture comes to a boil. Let it boil for 3 minutes without stirring.
Pour the caramel mixture evenly over the saltine crackers, spreading it gently with a spatula to coat all the crackers.
Bake in the preheated oven for 5-7 minutes, until the caramel is bubbly and has started to darken slightly. Keep a close eye to avoid burning.
Remove the baking sheet from the oven and immediately sprinkle the chocolate chips over the hot caramel. Let it sit for 2-3 minutes until the chocolate chips soften.
Using a spatula, spread the melted chocolate evenly over the caramel layer. If desired, sprinkle the chopped nuts and a pinch of sea salt on top.
Allow the candy to cool at room temperature for about 30 minutes, then transfer it to the refrigerator for another hour to set completely.
Once set, break into pieces and serve!