Chocolate Cupcakes with Rainbow Buttercream

I’m a holiday person. I love them, even the silly ones like Valentine’s Day. There’s really only one glaring exception, and by now you’ve probably figured it out given the lack of any posting about St Patrick’s Day this week. I don’t dislike St Patrick’s Day, I just can’t seem to get excited about it the way I do other holidays. As in years past, the extent of our celebration will be the corned beef and cabbage I’ll make for dinner this weekend. It’s one of Shane’s favorite meals all year, I’m pretty sure he’d happily eat corned beef every night if I served it :)

Chocolate Cupcakes with Rainbow Buttercream

I know not everyone shares my feelings, though, so I wanted to give you at least one recipe that would be fun if you are celebrating St Patrick’s Day this weekend. Not surprisingly, I chose to go the dessert route. I’ve already blogged a few of the more traditional Guinness stout recipes you usually see this time of year, so those were out. I’ve never made any rainbow treats, however, and every time I see them, I marvel at how cool they look. What better time of year to make them than St Patty’s Day, with that whole pot of gold at the end of the rainbow tale?

Chocolate Cupcakes with Rainbow Buttercream

I couldn’t love this rainbow colored frosting more if I tried – it’s one of those things that’s really simple to do, but has such a wow factor no one would ever know! Notice I said simple, but not fast. This definitely requires a little bit of patience and time. In essence, you are painting stripes of color into a pastry bag which then tint the frosting as it is piped. I did six colors of the rainbow, but this would work with any combination of colors so it’s easily customizable for other holidays or celebrations. And yes, I’m already dreaming of the next one I want to make :)

Rather than go with an old favorite, I tried a new chocolate cupcake recipe for the base here. The texture of these cupcakes was absolutely perfect – light and fluffy, but not too crumbly. The chocolate flavor was not quite as strong as I’d have liked, but I’d definitely make this recipe again. I used my go-to vanilla buttercream for the rainbow frosting. It’s super simple to throw together, and has a great consistency for piping.

If you’re looking for more St Patrick’s Day ideas, here are a few other treats from the archives:

Chocolate Stout Cake
Mint Chocolate Chip Cupcakes
Whole Wheat Irish Soda Bread
Guinness Cupcakes with Bailey’s Frosting
American-Style Irish Soda Bread with Raisins and Caraway Seeds

Chocolate Cupcakes with Rainbow Buttercream
cupcakes from Food and Wine, frosting from Cook’s Illustrated, rainbow idea from Chica and Jo

Cupcakes
4 tablespoons unsalted butter
1/4 cup vegetable or canola oil
1/2 cup water
1 cup all-purpose flour
1 cup granulated sugar
1/4 cup plus 2 tablespoons unsweetened cocoa powder (not Dutch process)
3/4 teaspoon baking soda
1/8 teaspoon salt
1 large egg, at room temperature
1/4 cup buttermilk, at room temperature
1 teaspoon vanilla extract

Frosting
10 tablespoons unsalted butter, at room temperature
1 1/4 cups (5 oz) confectioners’ sugar
pinch salt
1 1/2 teaspoons vanilla extract
1 tablespoon heavy cream

Preheat oven to 350 F. Line a 12-cup muffin pan with paper liners.

Add the butter, oil and water to a medium saucepan. Set over low heat and, swirling the pan occasionally, melt the butter completely.

Meanwhile, sift the flour, sugar, cocoa powder, baking soda and salt together into a large heatproof bowl. Pour the melted butter mixture over the top of the dry ingredients, and using a hand mixer, beat on low speed just until everything is incorporated. Beat in the egg until smooth, and then the buttermilk and vanilla. Run a rubber spatula along the bottom and sides of the bowl to make sure all of the ingredients are evenly incorporated.

Divide the batter among the liners in the muffin pan, filling each about 3/4 full. Bake for 20-22 minutes, or until a toothpick inserted in the center comes out clean and the cupcakes spring back when lightly pressed. Transfer the pan to a wire rack and let the cupcakes cool for a few minutes before removing them from the pan to cool completely.

To make the frosting: Beat the butter on medium-high speed in the bowl of a stand mixer fitted with the whisk attachment until smooth, about 20-30 seconds. Add the confectioners’ sugar and salt and beat on low speed just until the sugar is incorporated (so it won’t fly all over you), then raise the speed to medium and continue beating until the butter and sugar are well combined, about 1 minute total. Scrape down the sides of the bowl then add the vanilla and heavy cream. Beat on medium until incorporated, then increase the speed to medium-high and beat for about 4 minutes, or until the buttercream is light and fluffy.

To color the frosting: You’ll need gel food coloring (not the liquid ones, they won’t work). I used rainbow colors – red, orange, yellow, green, blue and purple – but you could do this with up to 6 colors in any variety you want. Fit a pastry bag with a decorative tip (I used a small star one) and set it in a tall glass. Paint stripes, about 1/2-inch thick, on the inside of the pastry bag. You want to leave some space in between each of the colors. The stripes should start down at the tip and extend up about 3-4 inches. Fill the pastry bag with the buttercream, then pipe until the frosting starts to display the colors of the stripes you painted (it’ll come out white at first, just keep squeezing the bag). Then you’re ready to begin piping onto your cupcakes in your preferred design. {Note: don’t try to refill the bag when you run out of frosting, you’ll need to start all over again, painting new stripes into a new bag.}

You can find more information on this process and photos here.

Makes 12 cupcakes