1. Preheat your oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper, leaving some overhang on the sides for easy removal.

2. In a medium saucepan, melt the butter over medium heat. Once melted, add the brown sugar and white sugar. Whisk continuously until the mixture comes to a boil.

3. Continue to cook, stirring constantly, for 5-7 minutes, until the mixture thickens and turns a deep golden-brown color.

4. Carefully pour the hot toffee mixture into the prepared baking pan, spreading it evenly.

5. Bake for 10-12 minutes, until the toffee is bubbling and has a slightly darker color.

6. Remove the pan from the oven and immediately sprinkle the cinnamon and salt over the top.

7. Allow the toffee to cool completely in the pan, for at least 30 minutes.

8. Once cooled, lift the toffee out of the pan using the parchment paper overhang. Cut into squares or rectangles and enjoy!