In a medium saucepan, combine the brown sugar, syrup, butter, and ¼ cup (60 ml) water. Clip a candy thermometer to the saucepan and set the pan over medium-high heat. Cook until the mixture reaches 245°F (118°C).
Add the cream and stir to combine, being careful not to let the hot syrup spatter on you. Halve the vanilla bean and scrape out the seeds. Add the see