Grapefruit Cake with Grapefruit Buttercream

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I baked this cake over the Easter weekend. It was my new baking experiment for which my in-laws were the guinea pigs.

The problem with new cake recipes is that you can never taste-test them prior to presenting them to your adoring, dessert-awaiting, crowd.

grapefruit cake 300x275 Grapefruit Cake with Grapefruit Buttercream

Unless you stealthily sneak a little bite from the underbelly of the cake…

…but I would never do that!!!…(?)…*coughs*…

So after having baked and “magically”-quality-controlled the new cake, I swiftly decided that the new kid on the block would, invariably, make all of the neighbourhood girls swoon.

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This cake straddles the line between sweet and tart and would make for a wonderful Spring or Summertime dessert. In our case, it provided a lovely alternative to an otherwise chocolate-laden Easter.

It was, instantly, a hit with everyone at the table, and will, assuredly, make a reappearance in my kitchen very soon.

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Grapefruit Cake with Grapefruit Buttercream

Adapted from the Pastry Affair

3/4 cup granulated sugar
Zest of 2 grapefruits
3 large eggs
1 cup light sour cream
1/2 cup kefir (or yogurt, or more sour cream)
1/2 cup extra virgin olive oil
2 teaspoon vanilla extract
1/2 cup freshly squeezed grapefruit juice (approx. 1 grapefruit)
3 cups cake flour (spoon 6 Tbsp cornstarch into a large measuring cup and fill with all purpose flour until the 3 cup mark is reached)
1-1/2 Tbsp baking powder
1 tsp baking soda
1/2 tsp salt

1. Preheat oven to 350 degrees F (180 degrees C). Grease and flour three 8-inch cake pans.
2. In a large mixing bowl, mix together sugar and grapefruit zest with your fingers until fragrant. Beat in eggs one at a time, mixing well between each addition. Mix in sour cream, kefir, olive oil, vanilla extract, and 1/4 cup grapefruit juice (reserve the other 1/4 cup for later).
3. Combine the flour, baking powder, baking soda, and salt. Stir the dry ingredients into the wet, until just combined.
4. Divide batter evenly between cake pans and bake for 35-45 minutes, or until a toothpick inserted into the center comes out clean. Using a pastry brush, brush remaining 1/4 cup grapefruit juice on top on the cake layers, allowing the juice to soak into the cake. Allow to cool to room temperature.

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Grapefruit Buttercream

1 cup freshly squeezed grapefruit juice
3/4 cup butter, room temperature
Zest of 2 grapefruits
6 cups powdered sugar
Milk or heavy cream

1. In a small saucepan, bring grapefruit juice to a boil and simmer until it reduces and thickens to about 1/3 cup. Cool to room temperature.
2. In a large mixing bowl, beat together butter and grapefruit zest until smooth. Mix in the reduced grapefruit juice. Gradually add powdered sugar until incorporated and smooth.
3. Slowly add milk or heavy cream, one tablespoon at a time, until desired consistency is achieved.

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Assemble: layer the cake with the buttercream and refrigerate until ready to serve.

  • Rachel @ Bakerita

    I’ve never considered grapefruit as a cake flavor, but it sounds oddly intruiging. I’ll be trying this out when I get my hands on some juicy grapefruits!

    • admin

      Hi Rachel :)
      I hope that you give it a try. I was also intrigued by the prospect and was definitely not disappointed.
      It’s very delicious.
      Thanks for stopping by!

  • Amrita

    I’d be part of that adoring crowd you know! That cakes looks super decadent and right up my alley.

    • admin

      Hi Amrita!
      It was fabulous. I had to INSIST that the in-laws keep the leftovers at their place. Otherwise, I would have eaten it for breakfast AND for dessert every day until it was finished. Pros and cons ;)

  • melissa

    does that say 15 tablespoons of baking powder?! not sure with the font I can’t tell if it says 15 or 1.5

    • admin

      Oh my gosh! So sorry. Yes, 1-1/2 Tbsp. Fixed!
      Thanks for pointing that out :)

  • Sara

    What an intriguing idea! As for the troubles of testing a new recipe, that’s the benefit of making cupcakes right? You can preview and no one’s the wiser.

    • admin

      YES! Another tried and true method ;)

  • Ems

    Does that say 15 T of baking powder?

    • admin

      Sorry! Didn’t realize that the font made it hard to see… 1-1/2 Tbsp. Thanks :)

  • melissa

    I thought that was a bit much LOL thanks for clearing that up I can’t wait to try this cake it sounds so refreshing!