The experience of biting into a perfectly created meringue mushroom is similar, I think, to biting into the center of a Pepperidge Farms Milano cookie, except on the best day of a Milano’s life, because instead of dampish shortcake, you have this wonderful crunchy meringue as your segway to the perfectly hardened chocolate morsel in the middle. (Divine.)
You’ll notice the ones here are just a little bit on the short-and-stout side rather than taller spriggly ones you might see in other photos on the Internet. That’s because I had two toddlers underfoot at the time and forgot to run my regular granulated sugar through the blender to make it superfine. They still came out delicious, if a bit on the short and squatty side. Seriously, though, if you can’t find superfine (castor) sugar at your regular discount market, do take the time to run your granulated through the blender first, and there’ll be no limit to the beautifully mounded stems and caps you can create.
(Eventually I’ll replace the photos up here with a new batch and then no one will ever need know I’m not perfect.) 🙂
Chef’s Note: I take a somewhat different approach to the baking/drying stage than you might see in other recipes. Instead of setting my temp to 200 degrees, baking for an hour, reducing to 175 degrees and then baking for an unknown additional amount of time, and constantly opening the oven door (adding humidity and removing heat!) to check them in the second hour, I opt for a much easier method which allows me to get other things done while the meringue is baking. I can even leave my house and run errands or play with my kids without worrying about keeping a close eye on the meringue! (I heartily recommend this alternative method below.)
Preheat oven to 375 degrees. Cover two cookie sheets with parchment paper or (very lightly) sprayed aluminum foil, shiny-side-down. In a mixing bowl, combine 4 room temperature egg whites with 1 cup superfine white sugar (or just run regular granulated through a blender for thirty seconds before adding to egg).
In an electric mixer, beat the mixture on HIGH speed for one minute, or until well-mixed. Add 1 tsp vanilla extract and about 1/2 tsp cream of tartar or meringue powder and return to HIGH speed. Beat several minutes, until meringue forms very stiff peaks.
As you’re checking this periodically, a good rule is that if you stop the beater, the mixture should stay in that rippled-mound form for at least 30 seconds after the beater stops moving. Or, you can use a spoon to pick up a bit of meringue and drop it onto the surface of the mixture. If it keeps its stiff upright shape for more than a few seconds, it’s ready to go.
(Alternately, a spoon should also be able to stand erect in the mixture without slipping or falling over.)
When the meringue is ready, fan open a gallon-sized freezer bag and rest, one point down, in a deep cereal bowl (or small prep bowl) to hold it upright and support it while you add the meringue.
Spoon meringue into the open piping bag. Twist the bag closed, and cut the pointed tip off the end of your filled piping bag. (Start with a very small tip; you can always make it bigger if necessary in a minute.)
Begin piping equal amounts of caps and stems onto your cookie sheets. The stiffness of the meringue should allow you to pull the caps upward and remain upright. When rounding your caps with the piping bag, make sure you disconnect your bag somewhere other than the very tops of the little domes, or they will dry with pointed tops like witch hats, which you probably don’t want. 🙂 If you do want to perform any minor smoothing before baking, wet your fingertips with water first to avoid sticking or unintentional pulling of the meringue.
Once all the meringue has been piped, they’re ready to bake. If you like, you can sprinkle the tops of the wet mushroom caps with cocoa powder to resemble dirt. You could also, alternately, make your mushrooms darker in color by whipping a small amount of cocoa powder into the meringue when you add the cream of tartar. It’s up to you.
Place the cookie sheets into the oven, shut the door, and IMMEDIATELY turn the oven completely off. Leave the mushrooms in the turned-off oven for at least 2 hours, or longer if you have another task to accomplish before finishing up the mushrooms.
(You can actually leave them in overnight if you want. The oven is a nice, dry environment for them to live in until you’re ready to assemble.) And, obviously, don’t open the door until you’re ready to assemble. Adding humidity or cooler air to baked meringue is prone to causing stickiness. Don’t worry about checking on them periodically — you turned off the oven when you put them in, so they won’t burn. Trust me.
Once baked, carefully loosen the caps and stems from the cookie sheet individually, taking your time. When all are loose, take a small, sharp knife and gently chisel a small, round nook (in drafting, we call this a countersink) in the center of the underside of each mushroom cap. This will create a space for the point of the stem to rest and keep them connected later.
Empty a small bag of semisweet chocolate chips into a stoneware bowl (plastic won’t hold the heat very long) and cover with plastic wrap. (Milk chocolate won’t hold its texture properly, so don’t even bother with anything but dark chocolate.)
Heat chocolate in the microwave for one minute on HIGH power; stir well and recover. Return to the microwave and continue heating for 15-20 second intervals, removing to stir each time. Don’t overheat or it will gum up on you!
When chocolate is melted, use a butterknife to smear chocolate around the underside of each mushroom cap, being sure to let a little sink into the stem hole you created. As soon as you coat each cap bottom, immediately insert the pointed top of a stem piece and press gently.
Place the assembled mushroom upside down (stems up) on the cookie sheet and allow to rest this way until chocolate has cooled and hardened, sealing the stem inside the cap. NEVER REFRIGERATE BAKED MERINGUE! (It will soak up humidity and go all sticky on you.)
Store in an airtight container. If you won’t be serving all of them within a couple of days, or if your weather is particularly humid, you can place a moisture-gathering agents under a sheet of waxed paper in the bottom of your airtight container, such as a sealed packet of Silica-Gel (like for drying flowers) or a cheesecloth square filled with dry rice and twisted shut with a string or twist-tie. A small piece of terra-cotta might also work. If you’re serving the meringue mushrooms within the week, however, you don’t really need to worry about it.
Chef’s Note: My mother, who makes these every Christmas, washes and saves random small plastic or foam produce cartons throughout the year, and then fills them with the meringue mushrooms as gifts for friends to make them look more authentic, like real mushrooms. They are so adorable. 🙂