I used this method for the fondant on my Rainbow Marble Mini Cake. As a rule, the more you roll out the fondant, the more the design stretches, changes and mutes the colors. I rolled out my fondant fairly thin, so I got areas that were much more muted. I’ve found that using a clay extruder to make the colored ropes of fondant, makes more defined lines of color. If you don’t have a clay extruder, no worries, it will still be beautiful! Remember, no two will be alike, which is part of the fun!
To make rainbow marble fondant you’ll need:
- 12 ounces white fondant to cover a 4-inch by 4-inch cake
- plastic wrap
- 6 quarter size balls of fondant in rainbow colors (about 1/4 ounce each)
- ruler
- cornstarch or powdered sugar for dusting work surface
- clay extruder (optional)
- knife or cutting tool
- fondant smoother
- rolling pin
*For optional gold highlights you’ll need
- edible gold luster dust
- vodka or lemon extract
- small food safe paintbrush
Knead the white fondant and form it into a 12-inch log. Cover with plastic wrap to keep it from drying out. Form rainbow colored balls of fondant into logs. Use extruder with 1/8 inch round die to make the logs into skinny ropes in each color. Cut into 12-inch lengths. You should have 2 12-inch ropes of each color. Alternately, if you don’t have an extruder, cut each log in half, lengthwise. Make the ropes by rolling the logs against your work surface with the palm of your hand, until they thin out and lengthen to about 12-inches. They won’t be perfect, but this will add to the character of your finished product.
Place one of each color of the ropes side by side, lengthwise on the log of white fondant. Press gently with fondant smoother to make sure the ropes adhere. Turn the log over and repeat with remaining ropes.
Twist log three or four times. Roll into a cinnamon roll shape. Flatten slightly with the palm of your hand. Roll out into a 12-inch circle. You should have a beautiful rainbow marbled piece of fondant ready to cover your cake. You can flip the fondant over and take a look at the other side if you wish. Both sides will have a different, interesting design, so you can choose your favorite! The design will continue to stretch and change as you apply the fondant onto your cake.
*If you want to add gold highlights, apply the fondant to your cake first. Once the fondant has set, mix edible gold luster dust with a bit of vodka or lemon extract to form a paint. Paint on highlights, following the lines of the marbling.