Sourdough Starter Discard Double Chocolate Truffle Cake

Sourdough Starter Discard Double Chocolate Cake

This is a quick and easy decadent chocolate cake recipe using only sourdough starter discard, with no extra flour added. It is extremely versatile, with simple ingredients a baker would have handy such as sourdough starter discard, butter, chocolate, eggs, sugar, salt, vanilla, and cocoa power. You can dress it up with a creamy chocolate glaze, hard ganache, whipped cream, simply dust with icing sugar, or serve plain.
 
This cake isn’t a very sweet cake, and perfect for chocolate lovers. If you want it sweeter, increase the sugar. If you prefer it to be less rich, decrease the chocolate and/or cocoa to your liking.

It is also versatile in the amount of sourdough discard you need from 1/4 cup to 2 cups. If you use 1/2 cup of the sourdough discard, it would be a truffle-like cake. If you use up to 2 cups of the sourdough discard, it will be a lighter cake. The adaptability is endless. 

Ingredients
 
*Measurements are provide for volume, as well as in imperial and metric weights. Bear in mind a cup of sugar does not weigh the same as a cup of butter.  Moreover, a U.S. cup (8.45 imperial fluid ounces) is not equivalent to a Canadian cup (8 imperial fluid ounces), Australian cup (8.80 imperial fluid ounces), Japanese cup  (7.o4 imperial fluid ounces), or U.K. cup (10 imperial fluid ounces), etc.
 
1 c (6 oz) 170g 6 semisweet chocolate squares or 1 cup chocolate chips
½ c (4 oz) 115g unsalted butter, cut into chunks
½ c (4 oz) 100g sugar, separated in half
½ tsp 0.5ml salt
½ tsp 0.5ml baking soda
1 tsp 1ml vanilla or 1 vanilla bean
6 large eggs, separated
¼ c (1 oz)  25g cocoa powder, sifted
½ - 2 c (4-16 oz) 100-400g sourdough starter discard at 100% hydration (room temperature) *Note: the volume of your starter varies depending on when it was fed and how active it is.
½ cream of tartar (optional)

Method

1. Preheat oven to 325 degrees F (165 degrees C). 
2. Grease a 9 inch spring-form pan (and line parchment paper, optional).
3. Melt chocolate with the butter. Cool.
4. Separate egg yolks from egg whites.
5. In a separate bowl, combine cooled chocolate/melted butter mixture, egg yolks, the other ¼ cup of sugar, salt, baking soda, vanilla, cocoa powder, and sourdough discard. Wisk until smooth. Do not overbeat.
6. With clean and dry beaters, whisk egg whites with cream of tartar (if using) until soft peaks. Gradually beat in ¼ cup of sugar until stiff peak. 
7. Slowly fold in 1/3 of the meringue mixture into the sourdough chocolate batter with a rubber spatula. Repeat twice more till just blended.
8. Pour the batter into the spring-form pan and run a spatula or knife through the battle to remove air pockets.
9. Place on second bottom rack in oven. 
10. Bake for 55-60 mins, or until a wooden skewer inserted into center of cake comes out clean.
11. Remove from oven. Let the cake cool in pan on top of baking rack for 5-10 minutes. Run knife along the side of the pan to loosen. Remove from pan and cool on rack (about 1.5 – 2 hours.
12. You may glaze the cake after it’s cooled or leave it plain.

 
Tips

• When separating egg yolks from egg whites, set up 3 bowls – two large, and one very small bowl large enough to hold one egg. Crack one egg into a small bowl first. Scoop out yolk gently from white and place in one large bowl. Pour the white into the other large bowl. This method ensures that should a yolk break, you only lose one egg, instead of a whole bowl of whites. Any yolk or oil in the whites will stop the whites from whipping up light and fluffy.
• You can whisk the egg whites before the yolk, butter, chocolate mixture, providing you do not leave the whisked egg whites standing for too long in order to ensure peak performance.
• Soft peaks in whisked egg whites means when you lift the whisk from the whites, the whites will form peaks that are slightly droopy. Stiff peaks means the peaks will be firmly pointing up. Do not overbeat.
• Measurements are provide for volume and in weight. I prefer to use weight measurements for precision as well as for easy clean up since you can weigh all the ingredients right in the mixing bowl.

Icing:
2 tsp 10ml icing

Sprinkle icing sugar through a sift on top of cake after the cake has cooled down.

Chocolate Ganache (Hard):
4 oz (bittersweet chocolate
½ c (4 fluid oz) 120ml heavy cream

Heat cream to simmer. Turn off heat. Add chocolate. Whisk until smooth.

Chocolate Glaze:
1 c 6 oz (150g) chocolate chips
1 TB 15ml unsalted butter
½ c (4 fluid oz) 120ml heavy cream
 
Heat cream. Add butter till melted. Add chocolate chips. Stir till smooth. Let sit 5-10 minutes till lukewarm. Pour over cake. If you don’t have cream, you can use milk, but use less milk to right consistency. Bear in mind that the glaze will be much thicker when cooled down.