Place granulated sugar and cinnamon into a small bowl, then mix to combine. Set aside.
Lightly grease a rimmed baking sheet with cooking spray, line it with a silicone baking mat, then place crackers side by side (they should be as close together as possible without overlapping) onto the prepared pan. Set aside.
Place butter, brown sugar, and salt into a large saucepan, then stirring regularly, bring the mixture to boil over medium/medium-high heat.
Once boiling, boil for 3 minutes, stirring constantly.
Pour slowly and evenly over crackers, trying your best to keep the toffee on the crackers, then bake in preheated oven for 5 minutes.
Remove from oven, sprinkle with cinnamon sugar mixture, then cool slightly before placing the pan in the freezer for at least 1 hour.
Break into pieces then enjoy frozen or chilled in the fridge.