This excellent flourless chocolate cake is a variation of a recipe that is most often attributed to Marcy Goldman’s A Treasury of Jewish Holiday Baking. The glaze suggested here is not from the original recipe.
The quality of the finished cake is entirely dependent on the quality of the chocolate that is chosen – take great care to choose an excellent chocolate.
1/2 cup (1 stick) butter
1/3 cup plus 2 tablespoons granulated sugar
6 large eggs, separated
1 1/2 cups cooked and mashed sweet potatoes, baked fresh and peeled – 2 or so
1 teaspoon vanilla
10 ounces good-quality gluten free semi-sweet chocolate chips, melted and cooled
1/4 teaspoon salt
Chocolate Glaze ingredients
1/4 cup water, 2 Tablespoons sugar, 1 Tablespoon corn syrup
4 ounces bittersweet gluten free chocolate, broken up
1 Tablespoon butter
Preheat the oven to 350°F. Line a 9-inch springform pan with baking parchment. To line the pan, first trace the bottom of the pan on a sheet of parchment paper, making a circle, then cut out the circle. Next, measure the height of the pan, and cut a strip of parchment paper that is that wide by 14 and a half inches long. Grease the pan, then line with the parchments paper, putting the circle on the bottom and the strip on the side. If you like, you can line the bottom and then clamp on the sides, trapping the circle of paper with the sides.
Cake batter instructions:
In a food processor, cream the butter with the 1/3 cup sugar until light. Blend in the egg yolks until light, then the mashed sweet potatoes, vanilla, and cooled chocolate. Mix until smooth.
In a large bowl, use clean beaters to whip the egg whites gently until they are a bit foamy. You can use a hand-crank-style manual rotary egg beater to do this – it is easy, and great exercise! Then add in the salt and whip harder to make meringue, sprinkling in the last two tablespoons of sugar to form stiff and shiny (but not dry) peaks. With this amount of sugar, you could also dump all the sugar in at once – it won’t make much difference.
Fold the cooled sweet potato/chocolate mixture into the egg whites gradually, keeping the mixture light and airy – don’t beat it now or you will lose all the air you have beaten in to the egg whites. The air trapped in the egg whites is what is going to make the cake rise in the oven.
Spoon the batter into the prepared pan, shake the pan briefly to settle it, and bake at 350 degrees for about 40 minutes (that is what the first version of this recipe said, but that was not correct – it took over 70 minutes). Depending on your oven, you will need to check the cake starting at 40 minutes, but leave yourself an extra half hour in case the baking takes longer. When the cake rises high and looks dry, and slightly cracked on top, it is done cooking – if it doesn’t look like this, give it more time. The middle should be soft but firm – a toothpick tests almost dry. The cake will have risen really high, but it will fall as it cools. Don’t worry about it though.
Cool in the pan for 20 minutes, then place the cake (in its pan) on a wire rack. Refrigerate completely to cool – overnight seems reasonable. At this point, the cake can be removed from the pan and frozen for up to a month (haven’t tried that). Even if serving it the same day, chill the cake for two hours before finishing it with the glaze. This is a dense cake which holds the heat.
In a pot, mix water, sugar and corn syrup and bring to a boil to dissolve the sugar. Off the heat add the chocolate (bittersweet is best). Stir until completely melted, then stir in the butter which will make it shinier.
Remove the cake from the pan, leaving the top side up. Do not try to flip it over. Put the cake on a serving plate. There will be a slight indentation where the cake has fallen in the middle. The final cake will have shrunk down from its lofty height that it was in the oven – maybe it will be 2 inches high. Pour the glaze into the indentation of the cake and, using a spatula, even out the glaze and urge it along to ooze attractively over the edges in places.
The cake is excellent served with whipped cream, and it seems like it would be pretty good if you used bittersweet instead of semisweet in the cake part too as well as the icing.
Make sure ALL your ingredients are gluten free. If you are making this for a gluten free friend, take care that there is no stray wheat flour in your sugar canister, transferred there during previous baking adventures.