Lime Cupcakes with Blackberry Buttercream

A combination of factors led to these cupcakes.

1. After making that raspberry buttercream, but knowing I could make it better, I was obsessed with creating a new berry buttercream, and the bag of organic blackberries in my freezer that I had purchased on sale for smoothies were just sitting there waiting for me.

2. I love lime. Always and forever.

3. Perhaps most importantly, I just watched 5 episodes of DC Cupcakes, a TLC program that showcases a cupcake shop in the capital. I find the scripted banter, escapades, and arguments particularly annoying on this show, but I sat through it for the cupcakes. As cupcakes go, these seem decent to me. I like that the frosting is standardized and the decoration minimal; these are signs that flavor is what matters to this bakery. And, inevitably, after watching hundreds of dozens of beautiful cupcakes being baked, decorated, sold, and shipped, I couldn't get cupcakes out of my mind. I had to prove that I could make a cupcake at least as delicious and whimsical as those two Greek sisters are doing in DC.

So I did.

Lime cupcakes with blackberry buttercream.

I followed the Tender White Cake recipe on the back of the King Arthur cake flour box, substituting fresh lime juice and zest for the almond extract. I can't imagine a more perfect white cupcake recipe. It's a gorgeous sponge whipped up with plenty of butter and egg whites, which makes the mixing process easier because you don't have to be so worried about overbeating.

I cooked the blackberries over medium heat until they broke down into a sauce. I strained them, and then beat the syrupy purple juice with a lot of butter this time, since the lack of butter was the problem in the raspberry recipe. I've made "dump icing" pretty much my whole life, so I just whipped the butter, whipped in the blackberry concentrate, and then added powdered sugar until I liked the consistency.

I did it. They are amazing. And my photos aren't bad this time, either! Take that, DC Cupcakes.

Raspberry Buttercream

As soon as I saw this recipe online, I knew my day would not pass before I had made it. My sister and I have been obsessed with making raspberry coulis for some time now--watching that magic tool, the fine-mesh strainer, turn seedy sauce into smooth ruby liquid. We've used it on pavlova, cheesecake, and coeur a la creme, but before this recipe, I hadn't considered the possibilities of whipping it with fat and sugar into a luxurious, tangy buttercream.

Courtesy of Brenda of A Farmgirl's Dabbles, I give you...  

Raspberry Buttercream.

• 1/2 c. unsalted butter, at room temperature
• 12 oz. raspberries, fresh or frozen
• 1/2 tsp. freshly squeezed lemon juice
• 3-1/2 c. powdered sugar
• pinch of kosher salt
• 1 to 2 T. milk, if needed to thin out the frosting   

Cook the raspberries in a medium saucepan over medium heat, stirring frequently until the raspberries are broken down into a sauce. Pour the sauce through a fine mesh strainer to remove the seeds, and then pour the raspberry sauce back in the pot. Simmer until the sauce reduces to a 1/4 cup. It will be a very rich red and concentrated sauce. Set aside to cool. With a mixer, cream the butter with a paddle attachment on medium high speed about 2 minutes, until lightened in color and a bit fluffy. Add 2 cups of powdered sugar, the 1/4 cup of cooled raspberry sauce, lemon juice, and salt. Mix until smooth. Add another 1-1/2 cups of powdered sugar and mix until smooth. If you want the frosting less stiff, add some milk, 1 tablespoon at a time. 

Frost whatever you wish! (Shown in this post on a prepared Dr. Oetker organic brownie mix.)

Edit: After tasting and re-tasting this recipe, and observing how it held up overnight, I actually wish I would have listened to my instincts and made this a truer buttercream by adding another stick of butter. Yes, another complete stick. If you look at a variety of buttercream recipes (like this and this), you'll find that if you're using over 3 cups of powdered sugar, the recipe should also contain at least 1 cup of butter, and this raspberry recipe only contains a 1/2 cup. Adding more butter would make the icing fluffier and more melt-in-your-mouth, though you might have to store it in the fridge. As it is, it's delicious, but extremely pasty-sweet because of the excess of powdered sugar.