1. In a saucepan over medium heat, burn the butter until it turns golden brown and gives off a nutty aroma, stirring occasionally. Remove from heat and set aside.

2. In a separate saucepan, combine the heavy cream, brown sugar, and light corn syrup. Bring to a boil, then reduce heat to medium-low and simmer for about 10 minutes.

3. Gradually add the browned butter mixture to the cream mixture in three parts, whisking constantly between each addition.

4. Increase heat to medium and cook until the mixture reaches 240°F (115°C) or the soft ball stage. Remove from heat and let it cool slightly.

5. Line a 10x25 cm (4x10 inch) rectangular baking dish with parchment paper and pour in the caramel mixture.

6. Sprinkle the surface with flaky salt. Let it cool to room temperature, then refrigerate for at least 6 hours or overnight until fully set.

7. Once set, lift the fudge out of the dish and cut it into pieces of your desired size.

8. Wrap each piece in wax paper or parchment paper and store in an airtight container at room temperature for up to 2 weeks.