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Grapefruit Poppy Seed Cake Recipe
Ben Carraoli

Grapefruit Poppy Seed Cake Recipe

I recently made this Grapefruit Poppy Seed Cake, and let me tell you—it was a showstopper! The tender, fluffy cake layers paired with tangy grapefruit curd and smooth cream cheese frosting instantly became a favorite in my kitchen. I love how bright and refreshing it tastes, perfect for any brunch or celebration.
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Total Time 1 hour
Ingredients Method Notes

Ingredients
  

  • 2 cups all-purpose flour – provides structure; sift for lighter texture.
  • 1 ½ cups granulated sugar – balances tartness of grapefruit.
  • 1 tbsp baking powder – helps the cake rise evenly.
  • ½ tsp salt – enhances flavor.
  • 1 cup sour cream – keeps the cake moist without using yolks.
  • 4 large egg whites – creates light airy texture.
  • ½ cup unsalted butter melted – adds richness and flavor.
  • 3 tbsp poppy seeds soaked in water 5 minutes – prevents seeds from absorbing moisture from the cake.
  • 1 tsp vanilla extract – rounds out the flavors.
  • Zest of 1 grapefruit – adds fragrant citrus note.
  • ¾ cup grapefruit juice – fresh is best for tangy flavor.
  • ¾ cup granulated sugar – balances tartness.
  • 2 tbsp cornstarch – thickens the curd.
  • ¼ tsp salt – enhances flavor.
  • 3 large egg yolks – gives the curd creamy texture.
  • 3 tbsp unsalted butter – adds richness.
  • 4 oz cream cheese softened – provides tang without overpowering.
  • ½ cup unsalted butter softened – creates smooth texture.
  • 2 cups powdered sugar – sweetens frosting evenly.
  • 1 tsp vanilla extract – enhances flavor.

Method
 

  1. Start by preheating your oven and greasing your cake pans. In a bowl, combine flour, sugar, baking powder, and salt. Soak your poppy seeds for 5 minutes, drain, and set aside.
  2. Whisk together sour cream, melted butter, egg whites, vanilla, and grapefruit zest. Slowly fold in the dry ingredients until just combined. Then, stir in the soaked poppy seeds gently.
  3. Pour batter evenly into prepared pans. Bake until a toothpick comes out with a few moist crumbs, about 35 minutes. Allow cakes to cool completely before assembling.
  4. Mix sugar, cornstarch, and salt in a saucepan. Add grapefruit juice and heat until slightly thickened. Temper the egg yolks by whisking in a small amount of hot juice, then add to the saucepan and cook until thick.
  5. Beat cream cheese and butter until smooth. Gradually add powdered sugar and vanilla extract, mixing until fluffy. This frosting balances sweetness with a tangy kick.
  6. Place one cake layer on a serving plate. Spread a generous amount of grapefruit curd, then top with the second layer. Frost the outside evenly with cream cheese frosting. Chill slightly for best results.

Notes

  • I always soak poppy seeds—it keeps the cake moist and prevents dryness.
  • I found using sour cream instead of egg yolks makes the cake incredibly tender.
  • I carefully watch baking time; overbaking dries the layers quickly.
  • I like to chill the cake briefly before frosting; it spreads smoother and cleaner.