Birthday Cake Club: Lemon Blueberry Cake

You've gotta try this fresh, new spin on a classic flavor combination!

Hello May Birthday Babies!

I probably say this every month, but I am so excited about this month’s Birthday Cake Club recipe. I mean, just look at it - so bright and sunny! Pockets of jammy blueberries are suspended in moist lemon cake and frosted with zesty citrus frosting. I hope you love it.

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Tart and tangy lemon pairs perfectly with sweet blueberries - it’s no wonder this is such a classic flavor combination. No need to wait for blueberry season either. This cake works with both fresh or frozen blueberries and homemade or store-bought jam.

I started thinking about this cake years ago. More specifically, the lemon buttercream.

With the exception of vanilla extract and instant espresso powder, I typically prefer to use the real deal when possible. It's not always for convenience, since who’s to say if it's more or less common to have fresh lemons versus lemon extract at home. But if there is a way to work in more flavor without challenging the integrity of a recipe, then I’ll try it. 

To make the lemon buttercream, I tried swapping out some of the water in an Italian meringue buttercream recipe for lemon juice. Italian meringue is made with a sugar syrup versus a Swiss meringue that is made with plain granulated sugar, so I hoped this swap would be a more effective way of providing lemon flavor instead of trying to add too much liquid (in the form of lemon juice) to the finished buttercream. Too much liquid added to the buttercream will break the meringue and butter emulsion.

Did it work? Mostly. I replaced a portion of the water in the sugar syrup with fresh lemon juice and was able to make a successful meringue. I wasn’t sure if there would be a negative chemical reaction between all that acid and the egg whites, but the meringue turned out great with a subtle lemon flavor. However, once all the butter was added, it still needed more. 

Lemon juice at both the start of the recipe and at the end was the answer to making this silky, citrus buttercream. The lemon flavor is fresh and subtle and it pairs perfectly with the less-sweet blueberry jam that I selected.

The batter is made to be quite thick in order to suspend the blueberries throughout the cake. I decided on a combination of sour cream and fresh lemon juice instead of buttermilk. Like buttermilk, sour cream is acidic and makes the cake super tender. Sour cream typically has a higher fat content than buttermilk, but mixing it with just enough lemon juice adds flavor and enough body to keep those blueberries from sinking to the bottom of the pan. 

The cake layers are fluffy and moist. I tested the recipe as a loaf and as muffins and the flavors and textures were spot on. You could eat the cake layers plain, but pairing them with the lemon buttercream and blueberry jam turns the whole situation into a party.