4 oz. good-quality bittersweet chocolate
(this is any chocolate with a cocoa solid over 65%)
1 stick unsalted butter
3/4 cup sugar
3 large eggs
1/2 cup unsweetened cocoa powder (sifted)
Preheat your oven to 375F. Find an 8 inch baking dish, butter the bottom and sides. Line the bottom with baking parchment, if you don't have any to hand I find you can cover the butter with a fine coating of sugar. It remains dry during the baking process and provides a little realease for the cake, but it doesn't work as well as parchment. Whatever the case, I typically only use the parchment for the bottom circle of the pan and use the butter/sugar trick for the sides.
Break the chocolate into pieces, about bite sized or a little bigger. Put it in a metal bowl and place the bowl on the stove over a pot of barely simmering water. Chocolate melts at around 85F (making big claims here....I'm not sure if my pastry memory serves me that well, but maybe I'll check my facts later). Anyway, it doesn't take much heat to melt chocolate, a good rule of thumb; melted chocolate should never feel much warmer than body temperature when you put your finger in it. And chocolate burns easily. It's not as tricky as I am making it all sound. Merely stir your chocolate occassionally being sure to scrape the edges of the bowl and if you see steam escaping the sides of your bowl/pot contraption, you probably have the heat too high.
On a separate burner in a small pot melt your butter on low heat. Once it is ready, and if your choclate is nearly all melted you can combine the two. If your choclate is not yet liquified continue to keep it over the simmering water. When done, take the pan off the heat and stir in the sugar. You may use a whisk or a rubber spatula, the trick is to use as few strokes as possible. The more air you introduce into chocolate the harder it becomes to handle. Again it's not as delicate as rocket science, it's simply something to be aware of while you work. Crack your eggs into a small bowl and beat them to break up the yolks. Touch your chocolate, if it is merely warm you may add your eggs; if it seems hot, let the mixture cool for a few minutes first.
With the addition of the eggs you are ready to add your cocoa powder. Please - sift your cocoa first. A pastry cook knows that cocoa clumps as it sits around in its container, secretly plotting to foil your favorite confections with dry lumps of bitter chocolate dust. Sifting it before use reduces those lumps and thwarts it's nasty plot. Please, please...sift. If you are fastidious you may even choose to sift it over your cake batter in three additions, gently folding the batter in between to incorporate the powder.
Pour the batter into the cake pan and take a moment to make it reasonably level. Voila! It's time to put your pan into the oven. I typically set the timer for half the recommended length and turn my cake when it buzzes. Keep an eye on this cake near the end of its cooking time. Overcooking it will strip it of much of its unctious moist goodness. It is done when a crust is beginning to form over the batter. Don't despair if you are lax in this respect, I have found the cake rising and cracking in the oven; after nervously puling it out, it cooled to a level appearance, and had retained enough moisture to be devilishly good.
Oh, it should take 25 minutes.