Easy Gluten-Free Exploding Rainbow Cake Recipe

Ingredients

Option 1: Homemade Gluten-Free Flour Blend Cake

1/2 cup plus 1 tablespoon sweet rice flour
1/2 cup white rice flour
1/2 cup plus 1 tablespoon tapioca flour
1/4 cup brown rice flour
3/4 teaspoon xanthan gum
1 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon kosher salt
1 stick unsalted butter, at room temperature, or 1/2 cup neutral oil
1 cup granulated sugar
4 large eggs
2 teaspoons pure vanilla extract
1/2 cup buttermilk, at room temperature
8 ounces sour cream, at room temperature

Option 2: Measure for Measure Flour Cake

2 cups gluten-free Measure for Measure flour
3/4 teaspoon table salt
1 1/2 teaspoons baking powder
1/2 teaspoon baking soda
3/4 cup plus 2 tablespoons milk
1/2 cup butter, softened
1 large egg
1 cup granulated sugar
1 tablespoon pure vanilla extract

For the Buttercream Frosting

4 1/2 cups confectioners’ sugar
2 sticks unsalted butter, softened
1 stick salted butter, softened
3 to 4 tablespoons heavy cream
1 1/2 teaspoons pure vanilla extract

Gel Food Coloring Option

1/2 teaspoon super red gel food coloring
1/4 teaspoon lemon yellow gel food coloring
1/4 teaspoon leaf green gel food coloring
1/4 teaspoon royal blue gel food coloring
1/2 teaspoon violet gel food coloring
1/4 teaspoon orange gel food coloring

Natural Dye Option 1

Red: 1 to 2 tablespoons beet juice
Orange: 1 tablespoon carrot juice
Yellow: 1 egg yolk
Green: 1 tablespoon spinach juice
Blue: 1 tablespoon or more blueberry juice
Purple: 1 tablespoon or more blackberry juice

Natural Dye Option 2

Red: 1/2 teaspoon red yeast rice powder plus 1/2 teaspoon beet powder
Orange: 1/4 teaspoon red yeast rice powder plus 3/4 teaspoon golden berry powder
Yellow: 1 teaspoon golden berry powder
Green: 1 teaspoon matcha powder
Blue: 2 teaspoons butterfly pea powder
Purple: 1 teaspoon purple sweet potato powder

For the Surprise Filling

1 to 1 1/2 cups rainbow sprinkles

or

1 to 1 1/2 cups candy-coated chocolates

or

1 to 1 1/2 cups colorful gluten-free candies

Optional Decorations

Rainbow sprinkles
Colored buttercream swirls
Edible glitter
Candy pearls
Mini marshmallows
Colorful cake toppers

Directions

Option 1: Homemade Gluten-Free Flour Blend Cake

Step 1: Prepare the Oven and Cake Pans

Preheat the oven to 350°F. Grease six 6-inch round cake pans and line the bottoms with parchment paper.

Step 2: Combine the Dry Ingredients

In a medium bowl, whisk together the sweet rice flour, white rice flour, tapioca flour, brown rice flour, xanthan gum, baking powder, baking soda, and kosher salt. Continue whisking until the ingredients are evenly distributed.

Step 3: Cream the Butter and Sugar

Place the room-temperature butter and granulated sugar in a large mixing bowl. Beat for 3 to 5 minutes, or until the mixture is pale and fluffy. If using neutral oil instead of butter, mix the oil and sugar until thoroughly combined.

Step 4: Add the Eggs and Vanilla

Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.

Step 5: Finish the Cake Batter

Add the flour mixture in three additions, alternating with the buttermilk. Mix just until combined after each addition. Fold in the sour cream until the batter is smooth and creamy. Avoid overmixing.

Step 6: Color the Batter

Divide the batter evenly among six bowls. Add a different food coloring or natural dye to each bowl, creating red, orange, yellow, green, blue, and purple batters. Stir each portion carefully until the color is evenly incorporated.

Step 7: Bake the Cake Layers

Transfer each colored batter to a prepared cake pan. Gently tap the pans against the counter to release large air bubbles.

Bake for 18 to 22 minutes, or until a toothpick inserted into the center of each cake comes out clean.

Step 8: Cool the Cake Layers

Allow the cakes to cool in their pans for 10 minutes. Carefully turn them out onto cooling racks and remove the parchment paper. Let the layers cool completely before assembling the cake.

Option 2: Measure for Measure Flour Cake

Step 1: Prepare the Oven and Cake Pans

Preheat the oven to 350°F. Grease six 6-inch round cake pans or coat them with nonstick spray. 

Line the bottoms with parchment paper.

Step 2: Cream the Butter and Sugar

Beat the softened butter and granulated sugar in a large mixing bowl until light and fluffy.

Step 3: Add the Egg and Vanilla

Mix in the egg and vanilla extract until completely incorporated.

Step 4: Combine the Dry Ingredients

In a separate bowl, whisk together the Measure for Measure flour, table salt, baking powder, and baking soda.

Step 5: Finish the Batter

Add the dry ingredients to the butter mixture in several additions, alternating with the milk. Mix just until the batter is smooth and fully combined.

Step 6: Color and Bake the Layers

Divide the batter evenly among six bowls. Color each portion with a different gel food coloring or natural dye.

Transfer the colored batters to the prepared pans. Bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out clean.

Step 7: Cool the Cakes

Cool the cake layers completely before frosting and assembling them.

Prepare the Buttercream Frosting

Step 8: Beat the Butter

Place the softened salted and unsalted butter in a large mixing bowl. Beat until smooth and creamy.

Step 9: Add the Sugar

Gradually add the confectioners’ sugar, approximately 1 cup at a time. Mix well after each addition.

Step 10: Finish the Buttercream

Add the vanilla extract. Beat in the heavy cream 1 tablespoon at a time until the frosting reaches a smooth, spreadable consistency.

Continue whipping the buttercream for 3 to 5 minutes, or until it is light and fluffy. If desired, divide some of the frosting among several bowls and tint each portion a different rainbow color.

Build the Surprise Center

Step 11: Prepare the Bottom Layer

Choose one cake layer for the base and leave it intact. Place it on a cake stand or serving plate. 

Spread an even layer of buttercream over the top.

Step 12: Cut the Center Layers

Use a round cookie cutter, biscuit cutter, or small bowl as a guide to remove the center from four cake layers. Leave the sixth and final cake layer intact for the top.

Step 13: Stack the Hollow Layers

Place one hollow cake layer over the base. Spread buttercream over the cake without filling the opening in the center.

Continue stacking and frosting the remaining hollow layers. Carefully align the openings to create a tunnel through the middle of the cake.

Step 14: Add the Surprise Filling

Fill the center cavity with rainbow sprinkles, candy-coated chocolates, or colorful gluten-free candies. Fill the opening nearly to the top without packing or overfilling it.

Step 15: Add the Top Layer

Place the final uncut cake layer over the filled center. Check that the cake is straight and that the layers are evenly aligned.

Frost and Decorate the Cake

Step 16: Apply the Crumb Coat

Spread a thin layer of buttercream over the top and sides of the assembled cake. This crumb coat traps loose crumbs and creates a smooth foundation for the final frosting.

Refrigerate the cake for 15 to 20 minutes, or until the crumb coat is firm.

Step 17: Add the Final Frosting

Cover the chilled cake with the remaining buttercream. Smooth the top and sides with an offset spatula or cake scraper.

Step 18: Decorate the Cake

Decorate with rainbow sprinkles, colored buttercream swirls, edible glitter, candy pearls, mini marshmallows, or colorful cake toppers.

For a dramatic finish, divide additional frosting among six bowls and tint each portion a different rainbow color. Pipe the colored frosting around the top edge of the cake.

Step 19: Slice and Serve

Present the cake whole before slicing so everyone can enjoy the colorful exterior. Cut into the center with a sharp knife and remove the first slice carefully to reveal the hidden filling.

Notes

Use either cake formula to prepare the six layers. Do not combine the two formulas in one batch.

The Measure for Measure flour must be specifically labeled gluten-free. Different flour blends can absorb liquid differently, so the texture may vary if another blend is substituted.

For the brightest rainbow layers, use concentrated gel food coloring. Gel colors add vivid color without introducing as much extra liquid as conventional liquid food coloring.

Natural colors may produce softer or more muted shades. Fruit and vegetable juices can also add moisture to the batter, so introduce them carefully.

Let every cake layer cool completely before stacking. Warm cake can soften the buttercream and cause the tall cake to shift.

If the tops of the layers are domed, level them gently with a serrated knife before assembling the cake. Even layers will produce a straighter, more stable finished cake.

When cutting the hollow centers, use the same cutter for all four middle layers. Align the openings carefully so the filling remains contained until the cake is sliced.

Do not cut the bottom or top cake layers. These intact layers seal the surprise filling inside the cake.

Check the labels on sprinkles, candy-coated chocolates, edible glitter, candy pearls, food coloring, cake toppers, nonstick spray, confectioners’ sugar, and other packaged ingredients. Products and manufacturing practices can vary, and not every decorating ingredient is gluten-free.

When preparing this cake for someone with celiac disease or gluten sensitivity, clean all tools and work surfaces thoroughly and prevent cross-contact with gluten-containing ingredients.

Store the assembled cake covered in the refrigerator. Allow it to sit briefly at room temperature before serving so the buttercream can soften.