2 c. granulated sugar
2 sticks butter (not margarine)
1 c. buttermilk
1 t. baking soda
1 t. vanilla
Put buttermilk, butter and sugar in a 2-quart sauce pan, and heat on medium high, stirring regularly. Bring just to a boil, then pull from heat and whisk in baking powder and vanilla. These last 2 ingredients will make it foam up quite a bit, that's why you want a larger sauce pan--otherwise it will overflow.
That's it for the basics.
After that, I'll add 1 teaspoon of any of the following extracts/flavorings: rum, banana, coconut, orange. My kids' favorite is the rum. I've also made a simple raspberry syrup with fresh or frozen raspberries, where you take about 1 c of them, mix them with 1/4 c of sugar, heat that over medium high heat, and stir/squish until it's a syrup. Then I add that to the buttermilk syrup base. You end up with raspberry cream syrup. Finally, I've also added about 1 t. cinnamon to the base, mixed in well, for cinnamon cream syrup.