Fresh Grapefruit Cake With Mascarpone Icing

This cake is a REVELATION.  I’ve had the idea stuck in my head since first watching the Great British Bake-Off episode where Beca makes grapefruit cake, since I’m a complete sucker for anything grapefruit flavored.  

This cake has a little of everything…light and buttery cake, tart but sweet grapefruit curd, and creamy not-too-sweet frosting.  It’s spring incarnate, my guilty pleasure, and heaven on a plate.

You’ll need a few pink grapefruit for this recipe, because it’s a more subtle flavor and you really want to pack it in.  

You can see the more detailed grapefruit curd instructions here, along with some extra tips.  In a small saucepan, whisk together the sugar and egg until smooth, then add the grapefruit juice and zest and turn the stove on medium heat (not too high!). 

Whisk continually for at least 5 minutes to thicken.  The mixture should be thick enough to coat the back of a spoon.  Remove the pan from the heat.  Add one tablespoon of butter at a time, whisking until each has fully melted before adding the next. 

Once all of the butter has been whisked in, transfer the curd to an air-tight container and refrigerate until completely cooled (it will keep thickening).

Preheat the oven to 355 F/180C.  Grease and line two 8-inch round cake tins.

Mix all the cake ingredients together using your stand mixer and the paddle attachment. 

Divide the mixture equally between the two tins and bake on the middle shelf of the oven for 25-30 minutes.  Allow to cool in the tins for five minutes, then turn out onto a wire rack.

Meanwhile, for the grapefruit sugar syrup, place the grapefruit juice and sugar in a small saucepan and bring to a boil.  Boil for around five minutes, or until the syrup begins to thicken.  Remove from the heat and cool slightly.

While the cakes are still warm, pierce the surface with a toothpick all over and drizzle the syrup evenly over both cakes (I definitely didn’t use all the syrup).  Allow to cool completely.

For the mascarpone cream, whisk the ingredients together until thick and airy, but not too stiff; a stand mixer works well but isn’t necessary.

Once it’s cooled, place the bottom layer of the cake onto a serving plate.  Spread half the mascarpone cream on the cake, and spoon a generous amount of grapefruit curd over that (some may spill over the edges).

Place the other cake on top and spread the remaining icing on top of the cake.

I use this amazing pink grapefruit curd recipe, and those are the ingredients listed below.  You can also make pieces separately and ahead of time, giving both the cake and the curd plenty of time to chill.

Other citrus treats you’ll love:

• The Most Amazing Moist Orange-Lemon Pound Cake
• The Best Homemade Key Lime Pie
• Lemon White Chocolate Lava Cakes
• Lemon Cupcakes with Raspberry Frosting
• Citrus Cake with Marmalade Filling and Lemon-Orange Icing
• Sweet Corn Cake with Tart Lemon Glaze

Adapted from PBS Food (originally from the Great British Bake-Off)

Fresh Grapefruit Cake With Mascarpone Icing

Yield: 1 cake

Prep Time: 10 minutes

Cook Time: 35 minutes

Additional Time: 1 hour

Total Time: 1 hour 45 minutes

This delicious grapefruit cake is bright and buttery, a perfect citrus treat!

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Ingredients

• For the grapefruit curd
• Scant 1/4 cup of sugar
• 1 large egg
• 1/3 cup of fresh pink grapefruit juice (1/2 to 1 grapefruit)
• Zest of 1 grapefruit
• 3 1/2 tablespoons of butter
• For the cake
• 200g / 7 ounces of sugar
• 200g / 7 ounces of butter
• 210g / 7 1/2 ounces of self-raising flour
• 4 large free-range eggs
• 25g / 1 ounce of ground almonds
• 1 grapefruit, zest grated and half the juice
• For the grapefruit sugar syrup
• 75ml of grapefruit juice (around 1 1/2 grapefruits)
• 75g / 2 1/2 ounces of sugar
• For the mascarpone cream
• 100g / 3 1/2 ounces of mascarpone
• 200g / 7 ounces of double cream
• 50g or 1 3/4 ounces of powdered sugar, sifted

Instructions

1. You can see the more detailed grapefruit curd instructions linked above.  In a small saucepan, whisk together the sugar and egg until smooth, then add the grapefruit juice and zest and turn the stove on medium heat (not too high!).  Whisk continually for at least 5 minutes to thicken.  The mixture should be thick enough to coat the back of a spoon. 
2. Remove the pan from the heat.  Add one tablespoon of butter at a time, whisking until each has fully melted before adding the next.  Once all of the butter has been whisked in, transfer the curd to an air-tight container and refrigerate until completely cooled (it will keep thickening).
3. Preheat the oven to 355 F/180C.  Grease and line two 8-inch round cake tins.
4. Mix all the cake ingredients together using your stand mixer and the paddle attachment. 
5. Divide the mixture equally between the two tins and bake on the middle shelf of the oven for 25-30 minutes.  Allow to cool in the tins for five minutes, then turn out onto a wire rack.
6. Meanwhile, for the grapefruit sugar syrup, place the grapefruit juice and sugar in a small saucepan and bring to a boil.  Boil for around five minutes, or until the syrup begins to thicken.  Remove from the heat and cool slightly.
7. While the cakes are still warm, pierce the surface with a toothpick all over and drizzle the syrup evenly over both cakes (I definitely didn't use all the syrup).  Allow to cool completely.
8. For the mascarpone cream, whisk the ingredients together until thick and airy, but not too stiff; a stand mixer works well but isn't necessary.
9. Once it's cooled, place the bottom layer of the cake onto a serving plate.  Spread half the mascarpone cream on the cake, and spoon a generous amount of grapefruit curd over that (some may spill over the edges).
10. Place the other cake on top and spread the remaining icing on top of the cake.

Notes

• You can make a lot of the component parts ahead of time, since the curd and cakes need time to cool. Then just assemble.