Super Moist Grapefruit Cake

This super moist grapefruit cake is a delightful balance of citrusy brightness and rich sweetness, topped with a creamy frosting that makes every slice irresistible. I love how the grapefruit adds a refreshing twist to a classic cake, making it perfect for spring gatherings or as a cheerful dessert any time of year.

Why You’ll Love This Recipe

I enjoy this recipe because the cake is unbelievably moist and packed with flavor. The grapefruit zest and juice bring a tangy freshness that pairs beautifully with the tender crumb. The syrup soaks into the cake, giving it extra juiciness, and the buttercream frosting rounds everything out with a smooth, creamy finish. It’s a cake that feels both special and comforting, and I always get compliments when I serve it.

Ingredients

(Note: All ingredient amounts are listed in the recipe card below.)

For the grapefruit cake:
2 cups all-purpose flour
1 3/4 teaspoons baking powder
1/2 teaspoon kosher salt
1 1/3 cup granulated sugar
1 Tablespoon grapefruit zest
2 large eggs
1 cup whole milk
3/4 cup canola oil
1 teaspoon vanilla extract

For the syrup:
1 cup grapefruit juice, from 2 grapefruits
2/3 cup granulated sugar

For the frosting:
1 container Pillsbury Buttercream Frosting
1 (1/2 cup) stick unsalted butter, softened
1/4 cup water

Directions

1. I preheat my oven to 350°F (175°C) and grease and flour a 9×13-inch baking pan or two round cake pans.
2. In a mixing bowl, I whisk together the flour, baking powder, and salt.
3. In another bowl, I combine the sugar and grapefruit zest, rubbing them together with my fingers to release the citrus oils.
4. I whisk in the eggs, milk, oil, and vanilla extract until smooth.
5. I gradually fold in the dry ingredients until the batter is well combined.
6. I pour the batter into the prepared pan and bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean.
7. While the cake bakes, I make the syrup by combining grapefruit juice and sugar in a small saucepan. I bring it to a simmer, stirring until the sugar dissolves. I set it aside to cool slightly.
8. When the cake comes out of the oven, I poke small holes in the top with a skewer or fork, then slowly pour the syrup over the warm cake to let it soak in.
9. For the frosting, I beat the butter until fluffy, then mix in the prepared buttercream frosting and water until smooth and spreadable.
10. Once the cake is completely cool, I spread the frosting evenly over the top.

Servings and Timing

This recipe makes about 12 servings. It takes me around 20 minutes to prepare, 40 minutes to bake, and another 30 minutes to cool and frost, for a total of about 1 1/2 hours.

Variations

Sometimes I swap the grapefruit zest with a mix of grapefruit and orange zest for a sweeter citrus flavor. I’ve also tried using a lemon glaze instead of frosting for a lighter finish. If I want a layered cake, I bake it in two round pans and spread frosting between the layers. For extra decoration, I sprinkle candied grapefruit peel or zest curls on top.

Storage/Reheating

I keep the cake covered at room temperature for up to 2 days or in the refrigerator for up to 5 days. To keep it extra moist, I store it in an airtight container. I don’t usually reheat this cake, but if I want a warm slice, I microwave it for a few seconds without frosting. The cake also freezes well either frosted or unfrosted for up to 2 months. I thaw it in the fridge overnight before serving.

FAQs

Can I use bottled grapefruit juice instead of fresh?

Yes, but I prefer fresh juice for the best flavor and brightness.

Can I make this cake without frosting?

Absolutely, I sometimes just drizzle the syrup and serve it as a glaze-style cake.

Can I use a different oil instead of canola?

Yes, I’ve used vegetable oil or even light olive oil with good results.

How do I keep the cake from being too bitter?

I make sure to zest only the colored part of the grapefruit peel, avoiding the white pith.

Can I make cupcakes with this recipe?

Yes, I bake them in lined muffin tins for 18–20 minutes and top each with a swirl of frosting.

What type of grapefruit works best?

I usually use ruby red grapefruits because they’re sweet and slightly less bitter.

Can I reduce the sugar in the syrup?

Yes, I sometimes cut the sugar to half if I want a tangier flavor.

Can I prepare the cake ahead of time?

Yes, I bake the cake a day in advance, keep it covered, and frost it just before serving.

How do I make the frosting less sweet?

I beat in some cream cheese with the butter and frosting for a tangier finish.

Can I add nuts or fruit to the batter?

Yes, I sometimes fold in chopped pecans or dried cranberries for extra texture and flavor.

Conclusion

This super moist grapefruit cake is one of my favorite citrus desserts. I love how the syrup keeps the cake soft and juicy, while the buttercream frosting adds a smooth, sweet topping. It’s a refreshing twist on a classic cake, perfect for any occasion when I want something bright, tender, and a little indulgent.

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