Today I’m excited to share a popular cake trend I’m seeing everywhere: Sprinkle Fault Line cakes, also called Sprinkle Geode Cakes. I first noticed this design on @cakedesignbysheri’s Instagram, and recently many bakers and decorators have adapted the look in their own styles.
Colorful sprinkle cakes are universally appealing, and one reason I love this trend is how easily it can be achieved with buttercream—though it can also be adapted for fondant cakes. If you search for sprinkle geode cakes, you’ll see variations inspired by geode cake techniques that use sprinkles in place of rock candy. The technique is versatile and lends itself to many creative directions.
In the video tutorial accompanying this article I demonstrate a spiral version of a sprinkle fault line cake, carrying the line all around the cake from top to bottom. Once you learn the basic method, the possibilities are endless: choose different sprinkle colors and sizes, experiment with smooth or textured buttercream, and vary the placement, width, and pattern of your “fault lines.”
We hope you enjoy the tutorial. If you have questions or try this method yourself, we’d love to see your results!
Table of Contents
Materials:
For this cake we made a double-barrel cake from four 6-inch layers. (This batch was our scratch yellow cake.) As usual, the first two layers were filled and supported with four bubble tea straws trimmed slightly shorter than the filled layer height. A cake board slightly smaller than the cake was placed on top of those layers, then the remaining two filled layers were added. To settle the layers we wrapped the cake in plastic wrap and placed a smaller 6-inch pan on top as a light weight, letting it rest for a few hours before frosting.
Classic Vanilla Buttercream Frosting — We used two batches of a butter-based vanilla buttercream, which firms up quickly when chilled and is helpful for smoothing.
Assorted sprinkles of your choice (we used a Wilton Diamond Medley)
Bench scraper and/or spatula for smoothing
Piping tips: Tip 4 for the bottom border and an 8B for French tip stars on top
Edible gold paint, or edible gold luster dust mixed with a small amount of everclear, vodka, or lemon extract; gold leaf is another option
Coloring gels — I used Sky Blue; note that buttercream with a slight yellow tint can shift blues toward blue-green
Miscellaneous: cake base or pedestal, two cake boards trimmed to size, a cake turntable to assist with frosting, and small paintbrushes for applying gold paint
Notes:
While our tutorial uses a double-barrel cake, this look works on any cake size, from single-tier rounds to sheet cakes. The technique scales nicely.
I frequently chill cakes briefly while decorating, especially before smoothing buttercream. Twenty minutes is usually enough to firm the frosting without freezing the cake. Avoid freezing the entire cake, which can lead to excessive condensation as it returns to room temperature.
If you need extra stability for a double-barrel cake during transport, you can drive a sharpened wooden dowel through the layers into the base. For a demonstration of dowel placement, see similar tutorial content demonstrating double-barrel construction and dowel installation.