Buttermilk Vanilla Cupcakes with Chocolate Sour Cream Frosting

As any baker knows, we’re often left with leftover buttermilk. This just happened to me this week; I made a chocolate cake with salted caramel filling and chocolate sour cream frosting for my father’s birthday dinner (sadly, no photos of this heavenly cake, as we were at a restaurant and I have no photos…) that called for buttermilk. I also made too much frosting, so I decided to spend the next evening whipping up a one-bowl recipe for vanilla cupcakes that uses buttermilk. And nothing better to use up chocolate frosting than a vanilla cupcake, so what an added bonus!

These are pretty much the perfect cupcake. Lightly vanilla-flavoured, they’re versatile enough to go with pretty much any frosting, or filling, or flavouring. Their texture is the cupcake-ideal: a little bit dense, a little bit airy, nicely moist. They’re really easy to make too; I didn’t even pull out the stand mixer, but just mixed it all together in one bowl with a spoon. For a straightforward, easy cupcake, these are the ones! I wouldn’t change a thing.

The chocolate frosting is a great choice for these cupcake and for any cake or sweet that demands a seriously chocolately and tangy frosting. I mixed together the sour cream and melted chocolate, and then just added icing sugar by the 1/2 cup, until I got to the flavour and consistency I wanted. I would guess I used 2 cups total, but it could’ve been more, could’ve been less. This is one seriously chocolate frosting!

Buttermilk Vanilla Cupcakes with Chocolate Sour Cream Frosting

Buttermilk-Vanilla Cupcakes with Chocolate Sour Cream Frosting

adapted from Martha Stewart

1 1/2 cups plus 2 tablespoons all-purpose flour
1 1/4 cups sugar
3/4 teaspoon baking soda
1/2 teaspoon baking powder
3/4 teaspoon salt
1 large egg plus 1 large egg yolk
1/2 cup plus 2 tablespoons warm water
1/2 cup plus 2 tablespoons buttermilk
1/4 cup plus 1 tablespoon vegetable oil
1 teaspoon pure vanilla extract

1. Preheat oven to 350 degrees. Line 12 muffin tins with paper liners.

2. Sift flour, sugar, baking soda, baking powder, and salt into a mixer bowl. Transfer bowl to mixer, and add egg, yolk, water, buttermilk, oil, and vanilla. Beat on low speed until mixture is well combined and smooth, about 3 minutes.

3. Divide batter among liners. Bake, rotating tins halfway through, until golden brown and a tester inserted into centers comes out clean, about 25-30 minutes. Let cool in tins. Invert cupcakes onto racks, and let cool completely. (Cupcakes can be stored for up to 3 days.)


12 oz semi-sweet chocolate
1/2 teaspoon instant coffee
1 teaspoon hot water
1 1/4 cup sour cream
icing sugar (about 2 cups)

1. Melt chocolate in a double-boiler.

2. Dissolve instant coffee in hot water. Stir coffee into the sour cream.

3. With a mixer, beat chocolate with sour cream. Add icing sugar, 1/2 cup at a time, to the chocolate mixture, until you reach the desired consistency and flavour.

Buttermilk Vanilla Cupcakes with Chocolate Sour Cream Frosting