6-7 egg whites (depending on how large), room temperature
1 t. cream of tartar
5 egg yolks
1 c. sugar
1/4 c. water
10 oz. butter, room temperature
2 oz. unsweetened chocolate, melted (opt), or 1 1/2 t. almond extract (opt)
1 c. heavy cream
12 oz. good quality, high content (60% or above) chocolate, broken into pieces
How to make it
Preheat oven to 225, and make sure your egg whites are at room temperature (cold whites do not whip well--NEVER beat egg whites cold, because you'll get almost twice the volume if you whip them at room temperature)
Grind 1 c. of the nuts finely with 1/4 c. sugar; these go into the meringue. Grind the remaining 1/4 c. nuts and reserve; these are for garnish.
Cover a large baking sheet with parchment. Using either a cake pan or the bottom of a springform pan, draw two 9-inch circles at either corner with pencil. Spray parchment with Pam, or butter.
Beat whites with cream of tartar until frothy. Add the sugar gradually as you beat the whites at low speed until all is added, then scrape down the sides of the bowl (to get all the undissolved sugar down into the whites), turn the speed up to high, and beat until you have stiff peaks, but it is still glossy and not dry.
Fold in the nuts/sugar mixture just until combined (you don't want to lose volume, and by the way, this means by hand -- you can't fold with a mixer).
Put the meringue into a large pastry bag with a plain tip, and pipe meringue around the circumference of each circle (you want to distribute the meringue evenly between the two, and the easiest way is to do both at the same time), then spiral inward and fill each circle. With a spatula or pastry knife, smooth the tops.
Put the baking pan in the oven and bake for an hour and a half. Turn the baking pan around, and bake for another half hour, until the meringues are dry all the way through. Turn off the oven, leaving the meringues inside, and let sit in the oven for an hour and a half.
Remove the pan, and VERY GENTLY remove each of the meringues from the parchment. Place on a rack and let cool to room temperature.
Ready? That was the easy part.
Make the ganache. Heat the heavy cream until simmering, then add the chocolate and turn off the heat. Stir until the chocolate is melted and fully combined, then pour into a mixing bowl and refrigerate for an hour. The ganache will have thickened quite a bit. Put in the mixer, and mix at high speed for a couple of minutes, to whip air into the ganache, then put back in the refrigerator.
Make the buttercream:
Put the egg yolks in a mixing bowl and place over hot water. Whisk until the yolks are hot to the touch. Remove and put under the mixer. Beat at high speed until the yolks have doubled in volume and leave a "ribbon" when you dribble them with a spoon.
Put the sugar and water in a heavy pan and cook over medium heat, stirring the sides down only until all the sugar is dissolved, until the syrup reaches 250.
With the mixer on high, very slowly add the syrup to the yolks, until all has been added. Continue beating on high until the mixture is ROOM TEMPERATURE. Still on high, beat in the soft, room temperature butter a tablespoon at a time, then refrigerate for an hour. (If using either flavoring, beat in just after you beat in the butter).
You're now ready to assemble the dacquoise. Place one of the meringues on a cake plate. Remove the buttercream and ganache from the refrigerator. First, beat the buttercream. You want it to be spreadable, but quite stiff. Then beat the ganache until smooth.
Fill the pastry bag (with either a plain or large rosette tip) with buttercream. Pipe a circle around the outside edge of the meringue, about a half-inch in. Now, pipe little "towers" on top of the circle of buttercream all the way around. This keeps your dacquoise from collapsing (reserve about a half cup of buttercream to decorate the top).
Inside the buttercream cavity, add the ganache. Place the other meringue on top, very gently pressing down to stick it all together. Pipe small rosettes of buttercream around the outside, sprinkle with the reserved chopped nuts, and if you like, sprinkle with powdered sugar and cocoa. Refrigerate for at least an hour before serving.