Whisk sugar, cream, and butter in a medium saucepan over medium heat.
Bring to a boil, stirring until the sugar is completely dissolved. Remove from heat.
Stir in vanilla. Let it cool slightly before drizzling over warm cake.
Notes
This glaze can easily soak your bread, so place it on a cooling rack rather than a plate before drizzling. Use a paper towel or sheet of aluminum foil to catch any drips.