Preheat your oven to 350°F (175°C).

Line a baking sheet with parchment paper and lay out the saltine crackers in a single layer.

In a medium saucepan over medium heat, combine the butter and brown sugar, stirring until it bubbles and turns golden brown, approximately 4-5 minutes.

Remove from heat and whisk in the heavy cream and vanilla extract until combined.

Pour the toffee mixture evenly over the saltines, spreading gently with a spatula.

Bake in the preheated oven for 10-12 minutes or until edges are bubbling and golden brown.

Sprinkle cinnamon and powdered sugar over the warm bars and let cool completely in the pan before cutting into squares.