Funfetti Birthday Cake

Before you start

Funfetti cake is a white or vanilla cake with rainbow sprinkles baked into the crumb, so each slice shows bright confetti flecks. The base here uses egg whites for a pale crumb that lets the colors show and the reverse creaming method, where butter is mixed into the dry ingredients first, for a fine, velvety texture.

The sprinkles decide whether the cake looks festive or muddy. Use rainbow jimmies, the long, thin sprinkles; they hold their color in the oven. Tiny round nonpareils and sanding sugar dissolve and bleed into gray-blue streaks. Fold the jimmies in at the very end with as few strokes as possible, because stirring smears their colors.

Ingredients

• Cake300 g (2⅔ cups) cake flour
• 300 g (1½ cups) granulated sugar
• 1 tbsp (12 g) baking powder
• ¾ tsp fine salt
• 170 g (¾ cup) unsalted butter — softened
• 60 ml (¼ cup) neutral oil
• 5 large (about 150 g) egg whites — room temperature
• 240 ml (1 cup) whole milk — room temperature
• 1 tbsp vanilla extract
• ½ tsp almond extract — optional; gives a bakery flavor
• 90 g (½ cup) rainbow jimmies
• Frosting340 g (1½ cups) unsalted butter — softened
• 480 g (4 cups) powdered sugar — sifted
• 3 tbsp heavy cream
• 2 tsp vanilla extract
• pinch fine salt
• 40 g (¼ cup) rainbow jimmies — for decorating

Method

1. Heat the oven to 175°C (350°F). Grease the pans, line the bottoms with parchment and grease the parchment.
2. Whisk the egg whites, milk, oil, vanilla and almond extract together in a measuring jug.
3. Mix the cake flour, sugar, baking powder and salt in the mixer bowl on low speed. Add the soft butter in pieces and mix on low for 1 to 2 minutes, until the mixture looks like damp sand with no large lumps of butter.
4. Add half of the liquid and beat on medium speed for 90 seconds to build structure. Scrape the bowl, then add the rest of the liquid in two additions, mixing on low for 20 seconds after each.
5. Add the jimmies and fold them in with a spatula in 5 or 6 strokes, just until scattered through the batter.
6. Divide evenly between the pans and smooth the tops. Bake for 28 to 32 minutes, until the tops spring back and a toothpick comes out clean. Cool in the pans for 10 minutes, then turn out onto racks and cool completely.
7. For the frosting, beat the butter on medium-high for 3 minutes, until pale. Add the powdered sugar gradually on low, then the cream, vanilla and salt, and beat on medium-high for 2 minutes, until fluffy.
8. Level the layers if needed. Spread about 1 cup of frosting between them, cover the cake with a thin crumb coat and chill for 15 minutes. Finish with the remaining frosting and press the decorating jimmies onto the sides or scatter them on top.

Tips for success

• Check the sprinkle label. Brands made with more starch and wax keep their color better in a batter.
• Toss the jimmies with 1 tsp of the measured flour before folding; they distribute more evenly and sink less.
• Bake the layers a day ahead, wrap them and refrigerate; cold layers are easier to frost.

Substitutions

Egg whites

Use 3 whole eggs for a richer, slightly yellow crumb. The sprinkles will still show, just against a warmer background.

Cake flour

Use 265 g all-purpose flour plus 35 g cornstarch, sifted together. The crumb is a little less fine but works well.

American buttercream

Swiss meringue buttercream is less sweet and silkier, and holds up well under decorations.

Variations

Funfetti cupcakes

Fill 24 lined cupcake cups two-thirds full and bake for 18 to 21 minutes.

Funfetti sheet cake

Bake in a 23 x 33 cm (9 x 13 in) pan for 32 to 38 minutes and frost the top only.

Troubleshooting

Sprinkles bled into gray streaks

Nonpareils or sanding sugar were used, or the batter was overmixed after adding them. Use jimmies and fold them in with a few strokes at the very end.

Cake is dense and tight

The butter was too cold or the batter was undermixed after the first liquid. Use soft butter and beat for the full 90 seconds.

Frosting is too stiff to spread

Add heavy cream a teaspoon at a time and beat until spreadable.

Storage

Keep the frosted cake covered at room temperature for up to 2 days, or refrigerate for up to 5 days and bring to room temperature before serving. Unfrosted layers freeze well for up to 2 months.

Safety notes

Do not taste the raw batter; it contains raw egg whites and flour. Contains wheat, egg and milk. Some sprinkles contain soy or other allergens; check labels.