Prepare the white wine–mirepoix mixture and reduce it by half as described for the classic method. Add 6 tablespoons (90 milliliters) mushroom essence and reduce the mixture again by half. About 6 tablespoons (90 milliliters) liquid should remain. Dissolve 3 tablespoons (45 milliliters) glace de viande in the hot flavor base. Check the consistency of the base; it should be lightly syrupy. If it is too thin, reduce it or add a bit more glace de viande. If it is too thick, thin it with stock. Whisk in 1½ ounces (45 grams) butter. Strain the sauce through a fine chinois.