Preheat your oven to 350°F (175°C) and line a rimmed baking sheet with parchment paper.

Place saltine crackers in a single layer on the prepared baking sheet.

Combine unsalted butter and brown sugar in a medium saucepan over medium heat; stir constantly and boil for 3 minutes.

Remove from heat and stir in vanilla extract until incorporated.

Pour the toffee mixture evenly over the saltine crackers and spread with a spatula.

Bake for 5-6 minutes, watching for bubbling and light golden edges.

Sprinkle cinnamon-sugar generously over the hot toffee.

Cool at room temperature for a few minutes, then chill in the refrigerator for 1-2 hours.

Cut into squares or break apart, and drizzle with optional toppings if desired.