Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper or aluminum foil and arrange the saltine crackers in a single layer.
In a small bowl, mix together the granulated sugar and cinnamon. Set aside.
In a small saucepan, melt the butter and brown sugar. Bring to a boil and let it cook for about 3 minutes until the mixture turns a deep caramel color.
Pour the caramel over the saltine crackers, spreading evenly with a rubber spatula to cover all the crackers.
Bake the crackers for 5-6 minutes, or until the caramel is bubbly.
Add the white chocolate: Remove the pan from the oven and immediately sprinkle the white chocolate chips over the hot toffee. Let the chips sit for 5 minutes to melt. If needed, place the pan back in the oven for about a minute to help the white chocolate melt.
Once melted, use a spatula to spread the white chocolate evenly over the caramel layer.
Sprinkle with cinnamon sugar: While the white chocolate is still wet, sprinkle the cinnamon-sugar mixture evenly over the top.
Let the toffee cool completely. For faster cooling, place the pan in the refrigerator for about 10 minutes. Once set, break the toffee into pieces and serve.