Combine brown sugar, corn syrup, and butter in a small heavy saucepan over medium-high heat. Cook, stirring constantly, until mixture comes to a boil. Boil gently, without stirring, for 2 minutes.
Remove from heat and, shielding hands with oven mitts, quickly whisk in baking soda. Stir in walnuts, dried cranberries, hot sauce and salt for 30 seconds or until mixture begins to set.
Mound the warm nut mixture on top of the Brie.
The cheese with mixture can be refrigerated until set. After it's set, cover and refrigerate for up to 2 days. Bring to room temperature before serving.