Balsamic Butttercream Sauce

Here is my recipe for Balsamic Buttercream sauce:

Balsamic Vinegar (enough to fill pan 1/4 inch)
1 Tbsp butter
1 generous splash red wine
1 pinch dried marjoram
1 pinch salt
1 Tbsp brown sugar

Fill a medium saucepan with 1/4 inch good Balsamic Vinegar. Add butter, wine, marjoram, salt, and sugar. Cook on low heat until reduced by half. Strain and return to pan (off heat). Add an equal part cream (or half-and-half) to the reduced liquid along with 1 more Tbsp butter. Return to low heat. Bring just to a boil, stirring constantly, and then remove from heat.