Strawberry Lemon Cupcakes
A few years back (three, to be exact) two of my friends were about to get married, and the bride asked me if I would make a groom’s cake for the rehearsal dinner. There were some very specific parameters - it had to be a spice cake because the groom is from the south and that's his favorite, and he's obsessed with batman. So, one custom batman cookie cutter order later, they had their cake. This year, to celebrate their anniversary they asked me to make cupcakes - Strawberry Lemon!
If you’ve read any of my other recipes you might already know that lemon is my favorite dessert flavor EVER, so I can make this frosting in my sleep. The cupcake recipe I adapted from my favorite strawberry cake recipe. It’s also one of the moistest and fluffiest cupcake recipes I’ve made (thanks Jello!), so it doesn’t even need a filling.
I love making celebratory desserts for friends and family, but I was especially excited to make these because my friend Corianna came over to hang out with me while I made them. She was producing a radio segment (3-4 minutes, I think) for graduate school about time and chemistry, and was particularly interested in how they both play a role in baking. We had a great time talking about technique, process, ingredients, and why baking is meaningful to me - I’m super excited to hear the final version! Corianna is also friends with the recipients of these cupcakes, so that was extra special. Check out her awesome work on documenting lives through oral history at http://ImpossibleQuestionsTour.com.
These are a perfect treat for someone you might want to celebrate with - Happy Baking!
Makes 18 Cupcakes
Adapted from Sweetapolita, Bravetart, and myself
This is for the frosting (and your face) and must be made at least 2 hours in advance.
4 ounces fresh lemon juice (from about 3-4 lemons)
4 ounces egg yolk (from about 5-7 eggs; save the whites for your frosting recipe!)
4 ounces sugar
Pinch of kosher salt
Zest of 1 lemon
Non-reactive saucepan, ideally a saucier (a pan with rounded bottom edges so there are no nooks for your curd to get stuck in and burn)
2 glass or ceramic mixing bowls
Fine mesh strainer that will sit atop one of your mixing bowls
Just a tip, aside from the extra cost and time to juice lemons and separate eggs, there is no reason not to double this recipe and have extra lemon curd because it’s the best and you can mix it with yogurt or put it on ice cream or freeze it or just go at it with a spoon because it’s AMAZING.
Set your strainer on one of the mixing bowls - set aside.
Simmer the 4oz lemon juice in your saucepan.
As it’s heating, in a mixing bowl whisk together 4oz egg yolks, 4oz sugar, pinch kosher salt, and zest of 1 lemon.
When the lemon juice has come to a simmer, very slowly begin adding some of the hot juice into the egg yolk mixture and whisking quickly.
This process is called tempering, where you VERY GRADUALLY want to warm up the egg yolks so they won’t turn into cooked egg yolk. If you added the yolk mixture to the hot lemon juice all at once it would turn into a gross scrambled mess.
Once you’ve added all the lemon juice and mixed to combine, transfer back to the saucepan and cook on medium heat, stirring constantly with your whisk until the curd has thickened and is starting to spurt big bubbles.
Yes, you have to mix constantly. You can be slightly more liberal about this in the beginning but once it gets hot enough to really start cooking, if you’re not constantly stirring it some of the curd will stick to the bottom and start to burn and that will both taste bad and also give it a weird brownish color.
Remove the pan from the heat immediately, and with your spatula add half or a little more of the mixture to your strainer. Use the spoon (or the spatula if you prefer) to push the curd mixture around in the strainer and press it through.
Repeat with the rest of the curd, scraping off the underside of the strainer with the rinsed-off spatula when you’re done.
If you want to speed up the cooling-to-room-temp process, you can transfer it to a stand mixer bowl and paddle it on low until it’s cooled. Otherwise...
Press plastic wrap directly onto the surface of the curd (do this if you’re going to let it sit to cool, or if you’ve just paddled it.)
Let the curd cool to room temperature, then chill for at least 1 hour.
1 stick butter, room temperature
1 cup sugar (200g)
1.5 ounces strawberry jello powder*
2 large eggs
1 and 1/3 cups AP flour (165g)
1.25 teaspoons Baking Powder
1/8 teaspoons salt
1/2 cup whole milk
1.5 teaspoons vanilla
1/4 cup seedless strawberry jam (mixed until smooth)
Two cupcake pans
18 cupcake liners
Medium mixing bowls/pyrex baking cups
Stand mixer with beater attachment
*If you want to avoid gelatin you could probably try using a Strawberry drink mix like Quik instead of Jello, or perhaps you could skip this altogether and use a 1/2tsp of strawberry extract and some pink food coloring instead. But - I can’t speak to how well this will turn out because I haven’t tried it! If you try it please let me know.
Preheat your oven to 350° F and put your cupcake liners in the trays
Beat your stick of butter, 200g sugar (1c) and 1.5oz strawberry jello on medium high for 2-3 minutes until light and fluffy.
Add 2 eggs, mixing until fully combined after each.
In a separate bowl, whisk together 165g AP flour (1.33c), 1.25tsp BP, and 1/8tsp salt.
In another bowl, whisk together 1/2c whole milk and 1.5tsp vanilla.
To your stand mixer bowl, add 1/3 of the dry mixture and mix on low until no flour traces remain, then add 1/2 of the wet mixture and mix on low until fully combined. Repeat twice then finish with the last of the dry ingredients.
Mix 1/4 cup strawberry jam until smooth, then add and beat on medium until combined.
Distribute evenly between your cupcake liners, filling each about 3/4 full.
Bake for 15-20 minutes - don’t overbake! They’re done when you press your finger into the top gently and it springs back, and doesn’t leave any indent. Start checking at 15 minutes, and re-check every 1-3 minutes until they’re done.
Let the cupcakes cool in their pans for 10-15 minutes before removing them. Let them cool completely before frosting or storing in the freezer (freeze them on a tray so they’re not touching each other, before you put them in tupperware or a freezer bag for long term storage).
LEMON SWISS BUTTERCREAM FROSTING
5 large egg whites (about 175g - each egg white is ~35g)
1 and 2/3 cup sugar (310g)
pinch of salt
1/4 teaspoon cream of tartar
5 sticks unsalted butter, cut into tablespoons, room temperature*
1/2-1 cup lemon curd
Optional: 1/2-1 teaspoon lemon extract
stand mixer with whisk attachment
small saucepan that will allow your mixer bowl to sit inside, but not touch the bottom
*If you’re making this last minute and your butter is cold, check out tip #7 here for quick room temperature butter. It’s really important that your butter isn’t cold, and also isn’t melty.
Place about an inch of water in your saucepan and bring it to a boil. Once boiling, lower heat to a simmer.
Add 175g egg whites (5), 310g sugar (1.66c), 1/4 tsp cream of tartar, and a pinch of salt to your stand mixer bowl, and hand whisk to combine.
Place the stand mixer bowl on the saucepan, so you’re creating a double boiler. Whisk vigorously by hand every two minutes or so, until the liquid reaches 185F on your candy thermometer, about 10-12 minutes.
Immediately place the bowl onto the stand mixer, and whisk on high until the mixture has turned glossy, and is not warm at all. This usually takes around 10-12 minutes. If you touch the outside of the bowl and it’s no longer warm, you can test the mixture with a clean fingertip to be sure. If you move on to the next step and it’s not fully cooled, you will not end up with frosting - you’ll end up with a soupy mess!
Once cool, reduce the speed to medium and begin to add your tablespoons of butter individually, with about 5 seconds in between each.
Once your mixture finally looks like frosting, add 1/2 cup of lemon curd and mix to combine. Taste, and add more to your liking.
Once you’ve added as much lemon curd as you want, if you’ve run out and you still want it to be more lemony, add up to 1tsp of lemon extract and mix to combine.
Use immediately or within a few hours. Can be refrigerated up to two weeks, and frozen up to a year or more. If you’re going to use it after chilling, let it come to room temperature completely before re-mixing to use.