Ingredients

1 1/2 cups freshly squeezed grapefruit juice

7 egg yolks

1 whole egg

1 cup granulated sugar

3 tablespoons grapefruit zest

⅛ teaspoon salt

5 tablespoons unsalted butter, cut into half-inch pieces

Pink food coloring (optional)

1 box white cake mix (plus ingredients needed to prepare it)

6 large egg whites

1 ¾ cups granulated sugar

½ cup water

1 teaspoon cream of tartar

1 tablespoon lemon juice

1 ½ teaspoons vanilla extract

Instructions

Make the Grapefruit Curd: Pour the grapefruit juice into a small saucepan and simmer over medium heat until reduced by half, about 3/4 cup remains. In a medium saucepan, whisk together the egg yolks, whole egg, and 1 cup sugar until combined. Whisk in the reduced grapefruit juice, zest, and salt. Add the butter and cook over medium-low heat, stirring constantly, until the mixture thickens, about 4 to 8 minutes. Stir in a few drops of pink food coloring if desired.

Strain and Chill the Curd: Immediately strain the curd through a fine-mesh strainer into a bowl. Cover with plastic wrap and refrigerate until completely cooled.

Prepare and Bake the Cake: Preheat the oven to 350ºF. Spray a 9×13-inch baking dish with nonstick cooking spray. Prepare the cake batter according to package instructions and pour it into the prepared dish. Bake for 23 to 28 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool completely.

Poke Holes and Add Curd: Using the handle of a wooden spoon, poke holes about an inch apart all over the cooled cake (about 60 holes). Pour the chilled grapefruit curd evenly over the cake, spreading it so it fills the holes. Use a skewer if needed to push the curd into the holes. Refrigerate the cake for about 2 hours to let the curd set.

Make the Meringue: Place the egg whites in a stand mixer bowl fitted with a whisk attachment and beat on high speed until stiff peaks form. Meanwhile, combine the remaining 1 ¾ cups sugar and ½ cup water in a small saucepan, cooking over medium heat without stirring until the syrup reaches 240ºF (soft-ball stage).

Combine Syrup and Egg Whites: With the mixer running at medium speed, slowly pour the hot sugar syrup into the egg whites in a steady stream, avoiding the whisk. Once all syrup is combined, add cream of tartar, lemon juice, and vanilla. Beat on high speed for 8 to 10 minutes until the meringue is glossy and cool to the touch.

Top and Finish: Spread the meringue evenly over the chilled cake using a spatula. Create decorative swirls with a spoon. For a finishing touch, toast the meringue lightly with a kitchen torch if desired.

Tips & Variations

Use a digital candy thermometer to accurately measure the sugar syrup temperature for perfect meringue texture.

Add a teaspoon of grapefruit liqueur to the curd for an adult twist on the flavor.

Substitute lemon zest and juice for grapefruit if you prefer a more traditional citrus flavor.

To make it vegan, try a white cake mix and aquafaba meringue, though flavor and texture will differ.

FAQs

Can I make the grapefruit curd ahead of time?

Yes, the grapefruit curd can be made up to 3 days in advance and kept refrigerated, tightly covered. Make sure to bring it back to room temperature before spreading it on the cake.

What can I use if I don’t have a kitchen torch for toasting the meringue?

If you don’t have a kitchen torch, you can briefly broil the cake under a preheated broiler to lightly toast the meringue. Watch carefully to prevent burning and remove as soon as it starts to brown.