Prep the pan: Line a 9x13-inch baking pan with foil or parchment, leaving overhang for easy lifting. Lightly grease the lining to prevent sticking.

Lay the crackers: Arrange saltines in a single, tight layer to fully cover the bottom. Break a few to fit the edges if needed.

Make the caramel: In a medium saucepan, melt the butter over medium heat. Stir in the brown sugar and bring to a steady bubble. Cook, stirring often, for 3–4 minutes until the mixture thickens and looks glossy. Remove from heat and stir in vanilla.

Pour and spread: Immediately pour the hot caramel over the crackers. Use a spatula to spread it evenly to all corners.

Bake briefly: Place the pan in a preheated 350°F (175°C) oven for 5 minutes. The caramel will bubble across the surface.

Add chocolate: Remove the pan and immediately sprinkle the chocolate chips over the hot caramel. Wait 2–3 minutes for them to soften, then gently spread into a smooth layer.

Finish with salt and toppings: Sprinkle a light pinch of flaky sea salt over the chocolate. Add any optional toppings while the chocolate is still soft.

Chill to set: Let the pan cool at room temperature for 15–20 minutes, then refrigerate for 1–2 hours until fully set.

Slice and serve: Lift the slab out using the foil or parchment. Cut into squares or break into “bark” pieces. Serve chilled or at cool room temperature.