Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper, and arrange the saltine crackers in a single layer, covering the entire sheet.

In a saucepan over medium heat, melt the unsalted butter and brown sugar together. Stir continuously until the mixture comes to a boil. Allow it to boil for about 3 minutes without stirring until it's bubbly.

Carefully pour the caramel mixture evenly over the arranged saltine crackers, ensuring each one is covered.

Place the baking sheet into the oven and bake for 5 to 7 minutes, or until the caramel is bubbly and golden.

Remove the baking sheet from the oven and immediately sprinkle the semi-sweet chocolate chips over the hot caramel. Allow them to sit for a couple of minutes, then spread the melted chocolate into an even layer.

If desired, sprinkle the chopped nuts and a pinch of sea salt over the chocolate layer for added texture and flavor.

Allow the Cracker Candy to cool for about 1 hour at room temperature, then refrigerate for at least 30 minutes to set completely before breaking into pieces.