How to Make a Stunning Rainbow Cake with Gold Ombre Layers
There's no gold waiting for you at the end of this rainbow ... but there's plenty inside!
Taste the Rainbow
Vivid rainbows that lead to a bountiful stash of gold are part and parcel of Irish folklore. What better way to celebrate St. Patrick's Day than with this showstopping layered rainbow cake with a gold ombre center? Start with the batter from this Classic White Cake recipe and this simple vanilla buttercream recipe, doubled. You'll also need: red, yellow and blue food coloring; gold sprinkles; a rotating cake stand or lazy Susan; three 8-inch round cake pans; a cooling rack; pastry bags or plastic baggies; rubber bands; a small offset spatula; scissors; a bench scraper or a large offset spatula.
Make the Batter
Once you've prepared the cake batter (the recipe should yield about 4 cups), divide it between 3 medium bowls, roughly 1 1/3 cups of batter per bowl.
Mix In the Color
Add 5 drops of yellow food coloring to one bowl, then 10 drops of yellow food coloring to another. One bowl will remain white. For an extra-deep-golden layer, add 20 drops instead of 10. You can use more or less food coloring to achieve your desired results.
Pour batter into three 8-inch round cake pans that have been prepared with baking spray and bake for 16 to 20 minutes, or until cake springs back up when touched in the center and it has pulled away from the sides. Invert cakes onto a cooling rack.
Prepare the Buttercream
While cakes are cooling to room temperature, prepare the rainbow buttercream. Using 6 bowls, add 1/2 cup of buttercream to each bowl.
Red: 5 drops red food coloring
Orange: 3 drops yellow, 2 drops red
Yellow: 5 drops yellow
Green: 3 drops blue, 2 drops yellow
Blue: 2 drops blue
Purple: 3 drops blue, 2 drops red
Fill the Piping Bags
Thoroughly mix the food coloring into the buttercream, then transfer each batch to a plastic disposable pastry bag. You can also use a sandwich baggie; just make sure it is not the stand-alone type with a pleated bottom. Secure frosting in bags with rubber bands and set aside. The remaining frosting will be used to crumb-coat the cake.
Place your cake stand (or plate) directly onto the rotating cake stand. Start by placing the darkest yellow cake onto the center of the cake stand. Drop 1 cup of buttercream on top of the cake. Then, using a small offset spatula, level the buttercream over the cake, making sure to allow the frosting to spill over the sides slightly.
Level the Buttercream
Once the buttercream is level and smooth, place the next layer of yellow cake on top. Drop another 1 cup of buttercream on top of that and level it in the same way you did before.
Add the Final Layer
Place the final layer of white cake on the top and drop another cup of buttercream on top of that. Carefully push the buttercream over the sides of the cake so that it spills down over the sides. Start in the center of the cake and let your offset spatula gently guide the buttercream toward the edges of the cake.
Crumb-Coat and Chill
Once you have frosting covering the sides, place the bottom of your offset spatula flat against the side of the cake and gently move it around the cake to smooth out the frosting. You can remove any excess, but do not reuse if the frosting has crumbs in it. Once the crumb coat is finished, chill the cake for at least 30 minutes in the refrigerator or 15 minutes in the freezer.
Add the Beauty Layer
Once the frosting is set, you will be covering the cake in the final (beauty) layer of frosting. Drop another cup of buttercream on top of the cake and smooth it over the cake the same way you did the crumb coat. Chill cake for at least 30 minutes in the refrigerator or 15 minutes in the freezer.
When you are ready to decorate the cake, cut off a very small portion from one corner of the purple frosting bag. (You can always cut off more if the hole isn't big enough to release frosting, so start small.) Now continue with the remaining bags. Place a dot of purple frosting at the base of the cake, then place a blue dot directly above it. Continue up with green, yellow, orange and finally red. You are doing this to determine spacing for your colors. If you need to adjust the spacing, gently wipe away the dots and start over.
Pipe the Purple First
Starting with the purple, pipe out a line around the circumference of the cake. (This is where the rotating cake stand really comes in handy!)
Repeat this process with the blue, green, yellow, orange, then red. Once you have all of the colors piped out, grab the bench scraper.
Smooth It All Out
Hold it flat against the side of the cake, then start moving it around the cake. If you are using a rotating cake stand, hold the scraper flat against the cake. then slowly turn the cake stand with your other hand.
Keep Going ...
The colors will flatten and gently blend together. Clean the bench scraper between uses.
... Until It Looks Like This
If you see spots of white showing through, simply go back and add dabs of the color you would like to fill in with. Slowly pull the bench scraper around the cake as many times as you want, to achieve a seamless look.
Add the Sprinkles
Gently drop the gold sprinkles around the edge of the cake. You can add as few or as many as you like. Once you're happy with the decorations, chill the cake until you're ready to serve it.
If they weren't already convinced of your baking prowess, your guests certainly will be once they see the vibrant bands of buttercream wrapped around their St. Paddy's Day dessert. But don't let on that there's a surprise inside! That way, when you cut the first slice, they'll really be in awe.