01 - Preheat oven to 350°F (175°C). Line a rimmed baking sheet (9×13 inches) with parchment paper or aluminum foil and lightly grease the surface.
02 - Lay saltine crackers in a single even layer across the entire baking sheet, covering it completely with no gaps.
03 - In a medium saucepan, melt the butter over medium heat. Stir in the brown sugar, cinnamon, and kosher salt. Bring to a rolling boil and cook, stirring frequently, for 3 minutes until the mixture thickens and becomes deeply bubbly.
04 - Carefully and evenly pour the hot toffee mixture over the arranged crackers, using a spatula to spread it into a uniform layer covering every cracker.
05 - Bake for 8 to 10 minutes, watching closely, until the toffee is bubbling vigorously and has turned a deep golden brown. Remove from the oven.
06 - Immediately scatter the white chocolate chips or chopped chocolate over the hot toffee surface. Let sit for 2 minutes to soften, then use a spatula to spread the melted chocolate into an even, smooth layer.
07 - In a small bowl, mix together the granulated sugar and ground cinnamon. Sprinkle the cinnamon sugar mixture evenly over the melted white chocolate layer.
08 - Allow the toffee to cool completely at room temperature, then transfer to the refrigerator and chill for about 30 minutes until fully set and firm.
09 - Break into irregular pieces by hand or cut into neat squares using a sharp knife. Serve immediately or store in an airtight container.