This grapefruit seltzer cake is a modern twist on 7Up cake

Here at the HelloGiggles office, we go through way too many cases of sparkling water every week. We didn’t think we could get any more obsessed with the stuff until we discovered this amazing recipe for Pamplemousse LaCroix cake. It’s sweet, pillowy, and totally like eating your favorite drink for dessert.

All you need is a little sugar, flour, and the LaCroix flavor of your choice. We can guarantee that if you bring this cake to a potluck, it’s sure to be the most unique treat there. Nothing makes a cake sparkle quite like sparkling water!

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Grapefruit Seltzer Cake



1 ½ cups unsalted butter, softened
1 vanilla bean, split in half lengthwise, seeds scraped and reserved
2 ½ cups granulated sugar
2 Tbsp. grapefruit zest
5 eggs
2 drops pink gel food coloring
3 cups all purpose flour
1 ½ tsp. kosher salt
1 Tbsp. baking powder
¾ cup grapefruit LaCroix
2 Tbsp. fresh grapefruit juice


2 ½ cups powdered sugar
1 Tbsp. fresh grapefruit juice
1 Tbsp. grapefruit LaCroix
2 tsp. grapefruit zest
1 drop pink food coloring
Pink rock candy, for garnish



1. Beat softened butter with vanilla bean seeds until light and creamy, 3-4 minutes.
2. In a small bowl, whisk together sugar and grapefruit zest. Gradually add sugar mixture to butter mixture, with the mixer motor on low. Once incorporated, increase speed to medium-high and beat until mixture is light and fluffy, 3-4 minutes.
3. Add eggs, one at a time, scraping down the sides of the bowl when necessary. Add food coloring.
4. Whisk together flour, salt, and baking powder in a medium bowl. In a separate small bowl, combine grapefruit LaCroix and fresh grapefruit juice.
5. Add flour mixture and LaCroix mixture to butter mixture in three parts, beginning and ending with flour mixture.
6. Pour batter into a greased and floured bundt pan and bake for 70-80 minutes, until a wooden pick inserted into the center comes out clean. (Cover with aluminum foil after 1 hour to prevent over-browning).
7. Let cake cool for 30 minutes in pan before turning out onto a wire rack to cool completely for an additional 30 minutes.


1. Whisk all ingredients together in a medium bowl. Drizzle over cooled cake. Top with crushed pink rock candy, if desired.