Lemon Rainbow Cake

I still remember the first time I saw a rainbow stretch across the sky after a summer storm on the farm; it felt like a secret promise from the heavens. Baking this lemon rainbow cake feels just like that—a quiet, unassuming exterior that hides a burst of joy and color inside, waiting to be shared. It is the kind of baking project that requires a little patience, just like the best things in life, but the smiles it brings to the table are worth every minute spent in the kitchen.

this Recipe

This recipe combines the bright, zesty tang of fresh lemons with the whimsical charm of six colorful sponge layers. Sandwiched with tart lemon curd and creamy vanilla buttercream, it is a tall, proud celebration cake that tastes as cheerful as it looks. Whether you are baking for a birthday or simply to brighten a gray afternoon, this cake is a labor of love that never fails to delight.

A Slice of Sunshine on a Plate

There is something truly magical about cutting into a cake and hearing the collective gasp of delight from your guests. This lemon rainbow cake is not just a treat for the taste buds; it is a feast for the eyes. The crumb is tender and buttery, enriched with plenty of eggs and milk, while the lemon zest cuts through the sweetness to keep every bite refreshing.

What I truly cherish about this recipe is its versatility. While it looks impressive enough for the grandest birthday party, the flavors are comforting and familiar—classic vanilla and bright citrus. It reminds me of the cakes we used to see in bakery windows downtown, tall and inviting, promising a special occasion even on an ordinary Tuesday.

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Pantry Staples & Fresh Flavors

To bake a cake this special, we start with honest, simple ingredients. Quality really counts here, especially with the butter and lemon, so use the best you can find.

• Butter or Baking Spread: You will need plenty of this. I use unsalted butter (softened to room temperature) for the buttercream to get that pale, creamy finish. For the sponge, a baking spread often yields a lighter crumb, but butter works beautifully too.
• Caster Sugar: This fine sugar dissolves quickly into the butter, creating the air pockets needed for a light sponge. If you only have granulated sugar, it will work, but the texture might be slightly less delicate.
• Free-Range Eggs: You need ten large eggs. It sounds like a lot, but they provide the structure and richness required to support six layers.
• Self-Raising Flour: This ensures an even rise. If you are using plain flour, be sure to add the appropriate amount of baking powder.
• Lemons: We use the zest for the sponge and lemon curd for the filling. Fresh zest contains the essential oils that give the cake its fragrant aroma.
• Food Coloring: To get those vibrant layers, you need concentrated gel colors (like Sugarflair or Pro Gel). Liquid food coloring from the grocery store often isn’t strong enough and can alter the batter’s consistency.
• Lemon Curd: A good quality jar is fine, but homemade is always a treat if you have the time.
• Rainbow Sprinkles: For that final touch of joy on top.

How to Bake It

Step 1: Prepare Your Tins and Oven

Start by preheating your oven to 320°F (160°C Fan / 180°C / Gas Mark 4). Grease and line your 8-inch cake tins with parchment paper. If you don’t have six tins (and who does?), you can bake in batches. I usually do three at a time.

Step 2: Mix the Batter Base

In a large mixing bowl, cream together half of the butter (275g) and half of the caster sugar (275g) until pale and fluffy. This aeration is the secret to a light cake. Add half of the eggs (5), half of the milk (1 tbsp), and half of the lemon zest. Whisk until fully incorporated.

Step 3: Fold in the Flour

Sift in half of the self-raising flour (275g) and gently whisk until you can no longer see streaks of flour. Be careful not to overwork the batter, or the sponges may become tough.

Step 4: Color the Layers

Divide this batter equally into three small bowls. This is where a digital scale is your best friend. Add red gel coloring to one, orange to the next, and yellow to the third. Mix gently until the color is vibrant and uniform.

Step 5: Bake the First Batch

Pour each colored batter into its own prepared tin. Bake for about 20 minutes, or until a skewer inserted into the center comes out clean. Let them cool in the tins for a few minutes before turning them out onto wire racks to cool completely.

Step 6: Repeat for Cool Colors

Wash your bowls and tins, then repeat Steps 2 through 5 with the remaining ingredients. This time, color your batters green, blue, and purple. You should end up with six beautiful sponges.

Step 7: Whip the Buttercream

While the cakes cool, make your frosting. Beat the softened unsalted butter (600g) and icing sugar (1.2kg) together. It will look sandy at first but keep going. Add the vanilla extract and a splash of milk (4-5 tbsp) and beat on high speed until it is smooth, pale, and spreadable.

Step 8: Assemble the Rainbow

Place the purple or blue layer on your cake stand (or start with red if you want the rainbow upside down!). Spread a thin layer of buttercream over the sponge, then drizzle generously with lemon curd. Repeat this process with all layers, stacking them in rainbow order.

Step 9: Coat and Decorate

Apply a thin layer of buttercream all over the cake to trap the crumbs (the crumb coat) and chill for 30 minutes. Once firm, smooth on the remaining buttercream for a thick, clean finish. Pipe rosettes on top and scatter with rainbow sprinkles.

Secrets from the Recipe Box

Over the years, I have learned that patience is the most important ingredient in a layer cake. Here are a few tips to help you get it right.

• Weigh Your Batter: To get perfect, even layers, I highly recommend weighing your mixing bowl before you start, then weighing the batter as you divide it. It ensures every slice looks uniform.
• Room Temperature Ingredients: Make sure your butter, eggs, and milk are all at room temperature before you begin. This prevents the batter from curdling and ensures a smooth emulsion.
• Gel vs. Liquid: I cannot stress this enough—use gel food coloring. It packs a punch without adding excess liquid, which could ruin the sponge’s texture.
• Chilling is Key: Don’t skip the crumb coat step. Chilling the cake sets the structure and makes applying the final layer of frosting much easier. If you want to learn more about the tools I trust in my kitchen, visit our about us page.

Make It Your Own

While I love the classic rainbow look, this recipe is a wonderful canvas for your own creativity.

• Citrus Twist: If you prefer orange or lime, simply swap the lemon zest and curd for your favorite citrus fruit. Orange curd with a splash of orange blossom water in the batter is delightful.
• Naked Cake: For a more rustic, vintage look, skip the final thick layer of buttercream. Scrape the sides so the colorful layers peek through the frosting. It has a lovely, farmhouse charm.
• Pastel Rainbow: Use less food coloring for a soft, pastel version. It is perfect for baby showers or spring teas.

If you try a new variation, we would love to hear about it! You can always subscribe to our newsletter for more baking inspiration delivered to your inbox.

At the Table

This cake is a showstopper, so it deserves to be the centerpiece. Because it is quite tall, I recommend using a sharp, hot knife to cut thin slices—a little goes a long way! It pairs beautifully with a pot of Earl Grey tea, which complements the lemon notes, or a cold glass of milk for the little ones.

Serve it on your favorite floral china to really bring out the vintage feel. If you are looking for more dessert pairings or beverage ideas, you can browse our recipe index at cakehalf.com.

A Final Slice

There is a special kind of pride that comes from placing a homemade layer cake on the table. This lemon rainbow cake is more than just flour and sugar; it is a memory in the making. I hope it brings as much color and joy to your kitchen as it has to mine. It is a recipe I believe Grandma would have chuckled at, but ultimately loved for its spirit.

If you bake this, please let us know how it turned out! You can reach out via our contact us page. We love seeing your creations.

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