Chocolate Cake With Purple Sweet Potato Cream
I lost 1 pound in two weeks…swell, right? Honestly, dieting is stressing me out…I definitely need a cheat day once a month. This chocolate cake sounds really delicious! I need to a test run for Saint Valentine’s cake anyway, D’accord? (agree?)..Oui, oui.
This cake is not overly difficult I think (delusional, perhaps)…it has lots of steps though…many dirty dishes to wash - I crammed most of them into the dishwasher but not all bowls fit in there…phew! To avoid being overwhelmed by lengthy instructions, I baked cake the night before.
Ingredients and Instructions for 1 cake (skip this process if you are using store bought chocolate sponge cake) (Print Recipe Here)
Necessary equipment – 1 round cake pan (7 inch cake pan prefer, 8 inch round pan is acceptable), parchment paper, food scale, food thermometer, sifter, stand mixer or hand held electric mixer.
- 3 eggs
- 1 egg yolk
- 100g granulated sugar
- 75g low viscosity flour (薄力粉)
- 15g unsweetened cocoa powder
- 15g milk
- 10g vegetable oil
- 20g butter
- Before you start, do A, B and C A. Get some parchment paper (do not use non-stick kind because it prevents the cake from rising, I used printer paper) cut to the size of round pan bottom and 1 inch taller than the sides. B. combine milk, oil and butter in a small bowl, double boil to melt and keep around 122F..C. Sift flour and cocoa powder 3 times.
- Set mixing bowl over a size smaller pan with hot water (water should not touch the bottom of top bowl) simmering. Beat eggs, egg yolk and sugar with whisk until temperature reaches 98F. Remove bowl from heat and run electric mixer on high (my stand mixer, speed # 8) for 7 minutes, change the speed to low (speed # 2), mix for 4 minutes.
- Start heating oven to 338F. With rubber spatula, sprinkle flour and fold in 4 sections. Scoop the batter from bottom of the bowl to gently incorporate. Turn the bowl 1/4 circle every time you put flour in. Do not over work this process and do this as quickly as possible.
- Check the temperature of milk mixture, if it is below 122F then warm up to right temperature. Use deep ladle to transfer one big scoop of batter into milk mixture and mix well. Back into the bowl of batter and fold in from bottom. 4-5 times.This step helps blend better than pour milk mixture straight into the batter.
- Fill batter into paper lined pan within an inch or so from the top Stir lightly over the pan with spatula to prevent center of cake to cave in. Hold pan with both hands and tap the cake pan on hard counter 2-3 times to remove air bubbles. Bake for 30 minutes. Insert wooden skewer to check the doneness. Remove from oven, drop the cake pan from 5-6 inches above counter, this helps prevent the cake from sinking. Remove the cake from the pan, place it on cooling rack for a few minutes.
- Remove paper from side and bottom. Place it up-side down on cooling rack. Wrap with plastic wrap while the cake is slightly warm, this will keep it moist
Ingredients and Instruction for Purple Sweet Potato Cream and Chocolate veneer (printable recipe at cake instruction)
Necessary equipment – food scale, food thermometer, non-stick parchment paper, electric mixer, fine mesh strainer
- 300g (about) Purple Sweet Potato, peel skin and cut in chunks
- 45g granulated sugar
- 45g milk
- 70g plus Chantilly cream – whip 100g of heavy cream with 1 Tablespoon sugar until soft peak
- 2-3 drops of rum flavoring (optional)
- 300g (about) chocolate shaved Note: I used Hershey special dark chocolate bar.
- Sweet potato paste – Place cut sweet potatoes in medium pan and pour in cold water, bring to boil then simmer until soft. Drain water through colander. put potato back in the same pan, shake the pan to remove the moisture with remaining heat. Add sugar, milk then smash potatoes with potato masher or fork while it’s still hot. Strain through fine mesh, this process enforces creaminess.
- When the sweet potato paste is cooled, add Chantilly cream 1/3 at a time and mix well to achieve soft but not too loose cream. Add rum flavoring if using and stir. Cover and keep in the refrigerator until needed.
- Prep for chocolate veneer – cut parchment paper to size – exact perimeter of the cake(s) x 1/2inch taller than cake height. Note: I was making individual cakes instead of 1 large, so needed 5,6 rectangular sheets. In order to make smaller cakes, just use a round biscuit cutter or a glass cup.
- Tempering chocolate – set aside a large bowl of 1-2 cups* of ice water. Double boil shaved chocolate (boil the water in pan, sit a bowl of chocolate on top, water not touching the bottom of the bowl) to melt, stirring frequently. When the temperature reaches 96F, remove from heat and carefully put in the ice water bowl so that water does not get in the chocolate, continue to stir to lower the temperature to 80F. Put bowl back in the double boiler, raise the chocolate temperature to 90F. *water level should not be over the chocolate bowl.
- Spread tempered chocolate evenly (do not spread too thick, especially if you want to achieve the delicate look) on the prepared parchment paper(s) using plastic spreader and let it (them) cool for 2-3 minutes
- Attach the chocolate/parchment sheet to side of cake(s). Refrigerate until chocolate is solid. Gently peel off parchment paper.Don’t be afraid of imperfection…distressed look is interesting, it adds drama!
- Construction – Put sweet potato cream in a piping bag with *tip attached (if the cream is very cold, microwave for 10-20 seconds with 50% power to loosen). Pipe out cream to fill space on top of cake. *Any tip but pinhole tip works.
Decorate with fruits (optional). I added Chantilly cream on a few.
I quickly distributed some to my neighbors…to avoid over indulging. I hope I’m not sabotaging their diet if they are on one …so far they’re gracious recipients.
Although this cake is mighty fine… maybe not that ONE for Valentine’s Day…keep searching…I thought we’re going out, my husband quipped…right,
Je sais (I know).