• In a large saucepan over medium heat, add the butter, sugar, buttermilk, vanilla extract, and corn syrup.

  Stir until the butter is melted and the mixture is well combined. Bring to a gentle boil.

  Remove the pan from the heat and carefully stir in the baking soda.

  Return the pan to the heat and stir constantly. The syrup will foam up and expand.

  Continue stirring for about 30 seconds, then remove from heat.

  Serve warm.

Notes

• Use a large saucepan, as the syrup will foam up quickly after adding the baking soda.

  If the syrup gets close to boiling over, remove it from the heat briefly while stirring.

  Leftover syrup can be stored in the refrigerator and reheated gently in the microwave or on the stovetop.