This started with a recipe from my sister (whom I love to antagonize).
10 egg yolks
10 egg whites
100 g sugar
350 g 60% dark chocolate
1 stick unsalted butter
100 ml Guinness draught
Pinch of salt
Scant ¼ tsp cream of tartar
Small glass jar for separating egg whites
2 ½ to 3 quart stainless steel bowl or sauce pan for egg yolks
Clean, dry 2 q/w quart mixing bowl, preferably of stainless steel for beating egg whites
Portable electric beater
Cover for the small saucepan holding the coffee
Larger pan with 1 inch or 2 of simmering water to hold the small pan for melting chocolate
Another and even larger pan with simmering water to set the egg-yolk pan into
1 or 2 rubber spatulas
Electric mixer on a stand for final beating of egg yolks
Egg yolks and sugar – preliminary blending. Start separating the eggs, dropping the white from number one egg into the jar, and the yolk into the stainless bowl or pan. Be sure there is no speck of yolk in the white – scoop it out with a bit of shell if there is, then transfer white into the egg-white beating bowl. Continue with the rest of the eggs. Set whites aside, out of the way. Using portable beater or wire whip, beat the yolks for 2 to 3 minutes until pale, lemon colored, and thick; this is a kind of anti-curdle insurance, and prepares them for being heated. You are now ready for the sugar syrup.
Set pan with 75 ml Guinness over high heat, blend in the sugar, and bring to the boil, swirling pan by its handle. Let boil a moment or two, swirling, until sugar has completely dissolved – liquid will be clear rather than cloudy. At once, bring hot liquid over to egg yolks; begin beating the yolks at moderate speed while you slowly dribble the hot syrup into them. Then set aside for a moment while you prepare the chocolate for melting.
Melting the chocolate. Stir the rest of the Guinness (25 ml) into the now empty sugar-boiling pan, and break the chocolate into it. Remove larger pan of simmering water from heat, place chocolate pan in it, stir up once, cover pan, and let chocolate melt slowly while you continue with the egg yolks.
Egg yolks and sugar – thickening over hot water. Set the egg-yolk pan in the second pan of water, and keep water at just below the simmer. Beat the yolk mixture rather slowly but continuously with portable mixer or whip for 5 minutes or longer, until it doubles in volume and becomes a thick cream that is hot to your finger. When warm and thick, scrape into the bowl of your electric mixer (or place egg-yolk pan in a large bowl of cold water). Beat at moderate speed 5 minutes or so, until cool, and when you lift a bit on a spatula it dribbles off in a thick ribbon that takes several seconds to dissolve and absorb back into the surface of the main body.
Combining egg yolks with melted chocolate and butter. Remove chocolate pan from the hot water and stir up; if not quite melted, renew hot water, and beat a few seconds, until chocolate is perfectly smooth and shining. Remove from hot water. Cut butter into 1-inch pieces, and beat it rapidly piece by piece into the chocolate, using electric mixer or whip. Scrape chocolate over egg yolks, then combine the two with a rubber spatula by cutting straight down through the center with edge of spatula, drawing spatula to edge of pan, then bringing it up to the surface in a scooping motion. Continue thus, rotating pan, and scooping rapidly until yolks and chocolate are fairly well combined. They will get more mixing later, and you need not be thorough as long as you are fast – about 30 seconds in all.
Beating the egg whites. At once, before chocolate and butter have time to cool and thicken, get to the egg whites. If they are chilled they won’t mount properly; set bowl in hot water and stir about for a few seconds until the chill is off, testing with your finger to see if they are room temperature. Being sure your beater is perfectly clean, start whipping the egg whites at moderate speed for a minute, until they are broken up and foaming. Add the salt and cream of tartar, and gradually increase speed to fast – circulating beater all about the bowl to incorporate as much air as possible, and taking about a minute to arrive at top speed. Continue until beater leaves definite traces in the egg whites, then begin testing. Egg whites should form stiff shining peaks when lifted in wires of eater, just the tops of the peaks bending down slightly. Proceed at once to next step. (“Stiff but not dry” is a phrase often used, but it is the shine and the sheen of them that you look for, since if you overbeat egg whites they lose that look, begin to break down, and turn grainy. But if this does happen, add another egg white, and beat again.)
Completing the mousse. Immediately turn one fourth of the beaten egg whites out on top of the chocolate with your rubber spatula; scoop and fold in rapidly to loosen the chocolate mixture. Turn the rest of the egg whites on top, and rapidly fold them in, just as you combined the chocolate and egg yolks, by rapid scoops with your spatula, rotating the pan or bowl as you do so. The whole process should not take more than a minute, and remember you are trying to deflate the egg whites as little as possible.