Advance prep: May be made 3 days in advance or frozen

1. PREHEAT oven to 350°F.
2. PLACE a piece of parchment on the counter and trace a circle around the bottom of a 9- or 10-inch (23- or 25-cm) springform pan. Cut out the circle.
3. GREASE the bottom of the pan with 1/2 teaspoon oil. Press the parchment circle on top. Grease the top of the parchment circle and the sides of the pan with the remaining oil. This step makes it easy to slide the finished cake onto a serving plate.

To make the cake:

1. MELT the chocolate and margarine over a double boiler, or use a heatproof bowl over a saucepan filled with simmering water, whisking often until thoroughly melted. You can also use a microwave oven, heating for 30-second increments and mixing after each heating cycle until melted. When the chocolate and margarine are melted, remove from heat, add the egg yolks and cocoa, and whisk well.
2. IN A SEPARATE BOWL, with an electric mixer on high speed, beat the egg whites until stiff. Reduce the speed to low, add the sugar, a tablespoon at a time, and mix. When all the sugar has been added, turn the speed up to high for 1 minute.
3. FOLD the egg whites into the chocolate mixture in four parts, mixing more slowly after each addition. Pour the batter into the prepared pan.
4. BAKE for 35 minutes, or until the cake is set when jiggled. The cake will puff up and look cracked on top, but do not worry about that. Let cool, and the cake will fall a bit. Place in the fridge a minimum of 4 hours or overnight.
5. WHEN YOU’RE READY TO SERVE, open the spring and remove the sides of the pan. Use a metal flat-blade spatula to separate the parchment circle from the bottom of the pan and slide the parchment and cake onto a serving plate. You may tuck pieces of waxed paper or parchment paper under the cake to keep the platter clean when icing the cake.

To prepare the icing:

1. POUR a few inches of water into the bottom of a double boiler or a medium saucepan and bring to a boil, then reduce the heat to medium. Off heat, place the sugar and warm water in the top of the double boiler, or in a heatproof bowl that can sit on top of the saucepan without falling in. Whisk to dissolve the sugar. Add the egg whites, honey, and salt and beat with a hand-held electric mixer for 1 minute on medium-high speed. Place the bowl over the gently boiling water and beat with the hand-held electric mixer on high speed for a full 7 minutes. Remove from the heat.
2. TRIM any dry pieces from the top of the cake. Eat them. If the top of the cake is uneven, you may place a piece of parchment on top of the cake and turn it over to ice the bottom as the top. Use a metal spatula to spread the icing on the sides of the cake, and then scoop up and spread the icing onto the top of the cake to cover it. You can smooth the top and sides or, if you plan to toast them with a blowtorch, use a small spoon to create waves or texture on top. Remove the waxed paper or parchment pieces from under the cake. Store the cake in the fridge. Use the blowtorch to brown the waved edges until a golden-brown color is achieved.

Bringing Egg Whites to Room Temperature in 10 Minutes:

1. Separate the eggs and place the whites in a metal bowl. Place the bowl over another bowl filled with 2 inches (5cm) of hot water. Stir the eggs occasionally and they will be at room temperature within 10 minutes.