Buttermilk syrup

It sounds strange, but one of my former library patrons suggested this syrup recipe. I tried it and it is delicious.

1 cup sugar
1 cube of butter
1/2 cup buttermilk (can substitute 1/2 cup milk and a little lemon juice)

bring to a boil and stir. Then add 1/2 tsp baking soda and 2 tsp vanilla. The mixture will foam up so don't be alarmed.