Put the chopped garlic and shallot in a saucepan with the wine and vinegar.
Put the saucepan over a medium heat and bring the liquid to a simmer. Cook until just over a tablespoon of the liquid remains then turn the heat down to low.
Whisk in the cream.
Add in a few cubes of butter and whisk quickly until it is thoroughly incorporated.
Add the remaining butter, a few pieces at a time and whisk continuously as it melts.
When you have just a few pieces left, turn off the heat completely and whisk the remaining butter in.
Season the sauce to taste before serving.
Keep it fluid in a water bath or bain marie to serve warm.