To a medium saucepan, add the butter, sugar, and buttermilk. Place over medium heat and whisk occasionally until the sugar is melted and everything is combined.
Bring to a boil. Whisking constantly, bring to a boil for 1 minute until the mixture becomes foamy.
Remove the saucepan from the heat and whisk in the vanilla and baking soda. Keep stirring as it foams up until mixed together.
Let cool slightly. Transfer to a serving container and serve over pancakes, waffles, or french toast.
Notes
Store any leftovers in an airtight container in the fridge.