In a saucepan, gently heat the brown sugar and the butter until both are dissolved, then add the corn syrup, then increase the heat and stir until golden brown. Add the cream, stir it in, and remove from the heat.
Serve hot or cold. Store covered in refrigerator.
Notes
You can use golden syrup instead of corn syrup. You could probably use whole milk instead of the cream, though the sauce might be a tad thinner.