Green Doors founder Allie here! I posted my (rather homely) 4th of July cake on our Instagram stories, and wanted to share my process with you in case you want to put something like this together for this weekend, or any of your upcoming summer gatherings.
(And to clarify, this refers to surface marbling, like paper, not marble like the stone.)
I made a couple of small loaves of olive oil cake, but you could absolutely start with a store-bought cake. And any shape and size will do! I flavored my cakes and my frosting with lemon because that's what I had on hand, but again, this will work with any flavor.
Here's the key to subtle, washed colors: I used food-based powders instead of food coloring. This is a great option if you want to avoid stains or mess, or are looking for something organic and plant-based. Just use caution if your have any allergy concerns. Keep reading for more.
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Don't make my frosting mistake
I made a ricotta frosting, which I think was not the best choice for marbling - a bit too thick for this technique, but oh so yummy!
A smoother, lighter frosting, or a thick icing would work best, I think.
Here's how I got a natural multicolor marbled frosting effect
I divided the frosting into thirds, so with my frosting recipe, I had about a cup of frosting for each color.
I left one portion white. I added about half a teaspoon of beet root powder to another portion for the pink, and the remainder was tinted hydrangea blue with butterfly pea flower.
Of course, use more powder for a deeper color. These are a little bit gritty, but do not have a distinct flavor.
I recommend you sift the powder first, or just be sure to break up any clumps with a fork before you add it to the frosting.
Then just stir and scrape to blend and thoroughly distribute each color through its portion of frosting.
I made little piping bags from waxed paper, but use whatever method and tools you're comfortable with to get the frosting laid down.
(A note about the powders: You can use them for other frosting projects of course, or use them as natural supplements in your coffees and teas. Just check in with a good herbalist and or your MD for any contra-indications.)
Create stripes of frosting
I tried two different methods to see which would work best with this ricotta frosting.
A. I piped a repeating pattern of frosting stripes directly onto the cake.
B. I put down a thick layer of plain white frosting first, then piped the colored frosting stripes on top of that.
I preferred the look of version A, but both worked fine.
You can play around with stripes of different widths, or a different repeat pattern, to get different effects in your natural multicolor marbled frosting.
How to achieve the marbling effect
I used a chopstick, but a toothpick would probably be best. You can see the gap where the thick ricotta frosting didn't fill back in...
Lightly drag the toothpick through the frosting stripes so they make ripples and break up the straight stripes. You can leave it like this if you like the scallop or fish scale effect.
Wipe the toothpick clean between each line.
Leave enough space between your "drag" lines so you can repeat the process in the opposite direction, again wiping the toothpick clean after each pass. This is how you get the soft chevron shapes in the photo at the very top of this page.
Clean up the edges by gently running the flat edge of a butter knife, or an offset spatula, around the sides of the cake.
Refrigerate for a couple of hours so the frosting sets.
Serve with fresh berries, or a berry reduction for a fun alternative to strawberry shortcake!
Try making multicolored whipped cream!
Of course you have my hearty endorsement to have a slice for breakfast. :)
Tag us on Instagram and let us know if you try this!
