Chocolate and Black Sesame Terrazzo Sheet Cake
Hello from puppy land! We’ve been watching our beloved step-dog, Hanky, the last few weeks so I’m up to my ears in dog snuggles and constant tug breaks. I’ve been 50% less productive but 200% happier while she’s been here. Her constant need of attention has caused a little break in recipe testing, but the timing actually worked out because my main focus at the moment is designing the pages of my book! It’s a somewhat acceptable work task in Hanky’s opinion because I can work on InDesign on the couch while she curls up at my feet. It wasn’t my intention to also play graphic designer on my book… but it just worked out that way. I’ll tell you more about it later!
Honestly, it’s been sort of fun to get back into design for a little. Yes, I did work in architecture but a lot of my job was laying out design presentations so that they were clean and easy to digest. Not too different from what I’m doing with my cookbook when you think about it. Moments like this make me thankful that I studied something creative with transferable skills. I think I would feel much more stressed out at the moment if I majored in Criminal Justice or something.
This Terrazzo Sheet Cake also brings me back to my designer days. I used to spend HOURS… days probably, reviewing terrazzo samples because it’s such a trendy material and every tech office in the city wanted terrazzo countertops in their break kitchens. I think it’s still trendy, right? So now instead of spending too much specifying terrazzo, I now spend too much time arranging shards of colorful white chocolate to make terrazzo sheet cakes. Life is wild! Despite the amount of time it takes to arrange the pieces, this cake decorating technique is so easy!
What is terrazzo?
Terrazzo is a composite material made up of small bits of marble, glass, or other hard materials like quartz or granite set into a cementitious base. Oooof, I sound too much like an architect there. But you get the idea!
For the base of the cake, you can literally use any cake or frosting combo. I used my favorite chocolate cake recipe and black sesame buttercream (both recipes below). I love how the black sesame looks like concrete with little bits of aggregate and sand. However, no shame in using a box cake mix! A funfetti terrazzo cake would be so fun!
Sheet cakes are underrated in my opinion. They are so easy to assemble. No need to stack layers or crumb coat. Just bake, cool, and slather on that delicious buttercream. It was brought to my attention recently that sheet cakes might be a super Midwestern thing. I mean, I had a sheet cake at literally every birthday growing up in Ohio so maybe that’s true.
Making the marble chips
Once you have your cake ready, it’s time to make the terrazzo chips! I used white chocolate because it takes on colors so well! If you’re a white chocolate hater… well, then you could make a very brown terrazzo cake with dark and milk chocolate. Or ruby chocolate if you’re into that!
I prefer to melt chocolate over a double boiler. A double boiler is a medium saucepan with about 2 inches of simmering water with a heat-safe bowl set over it. The simmering water will gently melt the chocolate until it’s smooth and luscious. You can however, melt the chocolate in the microwave. You need to be patient and only microwave in 20 second increments and stirring in between. It will take a few minutes, but this is the only way to prevent your chocolate from burning!!! I learned that from my high school chocolate shop job. Make sure to not get any water in the chocolate or it will seize up!
Once the chocolate is smooth, divide the chocolate into 3 microwaveable bowls or more if you want more colors. It’s nice to make sure the bowls are microwave safe just in case they cool a little too much and need a quick zap to get melty again.
Add your preferred colors into each bowl and mix until you’re happy with your palette. You only need tiny drops. To get more muted colors I like to add the tiniest drop of brown in there.
Line a baking sheet with parchment paper and spread the chocolate into a thin layer. Allow the chocolate to cool on the counter or in the fridge until it’s firm.
With a sharp knife, cut the chocolate into small and large chunks. You don’t have to be too precise! Now you have your terrazzo chips and you’re ready to arrange them on the cake.
The chocolate oddly tastes like Easter candy, maybe it’s the food coloring?
Laying out the terrazzo
There’s no real technique here! The people who layout terrazzo, like the old school artisans from Italy, will take as long as they need to layout the perfect balance of marble chips. While you don’t need to spend over an hour doing this, it did take me a decent amount of time to arrange the chips so that the colors and shapes were well balanced.
It’s almost like a puzzle, but there’s no right or wrong piece. Start with one piece and then build on that piece by finding the color and/or shape that you think will fit perfectly next to it!
How to cut a terrazzo cake
I think a lot of people will have this question! You have 2 options! You can either not care about clean cuts and confidently cut down through the chips and have rugged. OR chill the cake for 30 minutes so the buttercream is firmer and then soak a really sharp knife in hot or boiling water to warm up the blade. When the knife is hot it will more cleanly cut through the terrazzo chips and you’ll get neat squares!
I just thought of a 3rd but really insane option… you could use a really sharp paring knife cut into the space between the chips and have really chaotic pieces of cake lol.
You do you. It’s your cake!
Chocolate and Black Sesame Terrazzo Sheet Cake
makes 1 9x13-inch sheet cake
Cake:
150g (1 1/2 cup) granulated sugar
220g (1 3/4 cup) all-purpose flour
100g (1 cup) cocoa powder
1 1/2 tsp salt
1 1/2 tsp baking powder
1 1/2 tsp baking soda
2 eggs
240g (1 cup) full fat coconut milk or buttermilk
1 tsp vanilla
100g (1/2 cup) vegetable oil
170g (3/4 cup) boiling water
Black Sesame Buttercream:
3 sticks butter, softened
2 cups powdered sugar
Pinch of salt
2 tbsp black sesame paste (store-bought or recipe below)
White Chocolate Terrazzo Chips:
10 oz white chocolate chips
food coloring of choice
Black sesame paste:
1/2 cup toasted black sesame seeds
1/4 cup canola oil
2 tbsp sugar
In a small food processor, combine sesame seeds, canola oil, and sugar. Blend until smooth and somewhat loose. Store in an airtight container until ready to use.
make the cake:
Preheat your oven to 350 degrees. Line a 9x13-inch cake pan with parchment paper.
Whisk to combine sugar, flour, cocoa, salt, baking powder, and baking soda in a large bowl. Whisk to combine eggs, coconut milk, vanilla, and vegetable oil in a medium bowl. Add the wet ingredients to the dry ingredients and mix until a few clumps of flour remain. Stir in boiling water and mix until smooth.
Pour the batter into the cake pans and smooth out the surface with an offset spatula. Bake until a tooth pick comes out of the center clean, 25 to 27 minutes. Set the cake over a wire rack and allow to fully cool.
Make the buttercream:
In the bowl of a standmixer fitted with the paddle attachment, combine softened butter, powdered sugar, salt, and black sesame paste. Mix on bowl until most of the powdered sugar has incorporated. Increase speed to medium and continue to mix until smooth and fluffy, 3 to 5 minutes. Scrap down the sides when needed.
Make the terrazzo chips:
Melt the chocolate in a double boiler until smooth. Divide the chocolate into 3 microwave safe bowls. Add desired food coloring to each bowl and mix until you’re happy with the colors.
Line a baking sheet with parchment paper and spread the chocolate into a thin later with an offset spatula. Allow the chocolate to firm up on the counter or in the fridge.
Once set, cut the chocolate into small and larger shards.
Assemble the cake:
Spread the buttercream over the cake into an even layer.
Arrange the terrazzo chips over the buttercream and gently press down to set.
Cut and serve.