Low Carb Grapefruit Cake with Whipped Frosting

Low carb grapefruit cake is lightly spiced with ginger and clove, then finished with a mascarpone and grapefruit whipped cream frosting.

It has been far too long for a new cake recipe around here. I have a deep love for making cakes and eating them as well. Making this grapefruit cake kick started me on making a variety of an additional three more cakes!

This low carb grapefruit cake is very moist and similar to a chiffon cake. Chiffon cakes are leavened with egg whites as this cake is but are traditionally made with oil and this cake is made with butter.

I have tried not to use the word “moist” when describing baked goods anymore. Using the word “moist” became a big deal in the food world and is almost forbidden to use anymore. I really don’t understand the big fuss.

What to Make with Grapefruit?

Over the holidays I purchased a very large amount of citrus fruits; really wanting to work on my photography skills and use citrus fruits to do so. After making many recipes including oranges, I couldn’t settle on what to do with the grapefruit.

A grapefruit brioche pastry was calling out to me but after all of the holiday cooking and baking, my heart just wasn’t in trying to create a low-carb or gluten-free brioche. I was running low on a few key supplies and knew there would likely be many failed attempts.

So, grapefruit cake it was. You can never go wrong with cake!

Help Baking and Photographing Grapefruit Cake

During the holiday season, for the first time ever, I had two little helpers. My mom helped me take a photograph that would’ve taken me hours to capture alone.

The second time, I was watching my nine year old niece for the day. She loves to bake and is always a helper in anyway you ask her.

I had baked the cake the previous evening so we had to make frosting and then take photographs.

Having someone help hold up a light diffuser is unbelievably helpful. She also took the photograph below and told me it was “good”. I trusted her instincts and didn’t even look at it before we moved on.

How to make Low Carb Grapefruit Cake

In a stand mixer with a paddle attachment or in a large bowl with a mixer, cream the butter until it is light and fluffy. Add the sweetener and combine well, then add the honey and grapefruit zest and mix well.

To the butter mixture, add the egg yolks, incorporating one at a time. Next, add the sour cream, vanilla, and freshly squeezed grapefruit juice.

Sift the almond flour, arrowroot flour, salt, coconut flour, ginger, and clove in a separate bowl. Incorporate the dry mixture into the wet mixture one-third at a time, scraping down the bowl after each addition.

Slowly combine the heavy cream, carefully to not whip.

In a separate bowl, whip the egg whites until they are a soft peak. Add two tablespoons of sweetener and whip until they reach a stiff peak.

Gently fold the egg whites into the batter until they are just incorporated and transfer to a parchment lined 8”x4” baking pan. Place in a preheated 325° oven and bake for 55-60 minutes.

If you do not have an 8”x4” pan, use a 9” pan.

For the Frosting

Whip the heavy cream until it reaches medium peaks. Fold in the grapefruit zest, juice, sweetener, and mascarpone cheese and thoroughly combine.

Wait for the cake to completely cool before frosting.

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Looking for more great recipes? Check out hummingbird cake and chocolate hazelnut cake.