Sauce a la Mirabeau

Pound three hard boiled egg-yolks with a handful of chervil and two tablespoonfuls of capers, adding a quarter of a pound of butter, a clove of garlic chopped and crushed; then rub the mixture through a sieve. Put into a saucepan a quart of veloute (No. 415) and two gills of chicken stock (No. 195); let it boil up; despumate the surface and reduce the whole, afterward adding very slowly the prepared butter, working it in the sauce with a whisk, season highly and strain through a tammy, heating it again before using.