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Grapefruit Poppy Seed Cake Recipe
Ash Tyrrell

Grapefruit Poppy Seed Cake Recipe

When I baked this Grapefruit Poppy Seed Cake for the first time, I couldn’t stop smiling as the fresh grapefruit scent filled my kitchen. I loved how the poppy seed layers stayed moist and soft, and the sweet-tart grapefruit curd made each bite so lively
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Total Time 2 hours
Ingredients Method Notes

Ingredients
  

  • 1 cup 226 g unsalted butter, room temperature — soft butter creates a light texture.
  • 1 ¾ cups 350 g granulated sugar — sweetens and keeps the cake tender.
  • 6 egg whites room temperature — helps keep the cake fluffy and pale.
  • 1 cup 240 g sour cream, room temperature — adds moisture and richness.
  • 1 teaspoon vanilla extract — enhances overall flavor.
  • 3 cups 345 g cake flour — produces a softer crumb than all-purpose flour.
  • 1 tablespoon baking powder — helps the cake rise properly.
  • 1 teaspoon salt — balances sweetness.
  • 1 cup fresh grapefruit juice — fresh juice gives the best citrus flavor.
  • 3 tablespoons poppy seeds — adds texture and signature taste.
  • 3 egg yolks — create richness and thickness.
  • ½ cup sugar — sweetens the tart juice.
  • 2 tablespoons cornstarch — helps thicken the curd.
  • 1 cup fresh grapefruit juice — provides bold citrus flavor.
  • 2 tablespoons unsalted butter — adds smoothness and shine.
  • Optional pink food coloring — for a soft blush tone.
  • 1 ½ cups unsalted butter — gives structure and creaminess.
  • 4 oz cream cheese — adds tangy flavor.
  • 6 cups powdered sugar — creates sweetness and stability.
  • 3 tablespoons heavy cream — makes frosting smooth and spreadable.
  • 1 teaspoon vanilla extract — enhances flavor.
  • Pinch of salt — balances sweetness.

Method
 

  1. Start by mixing the dry ingredients in one bowl and creaming butter and sugar in another. Add egg whites gradually, then sour cream and vanilla. Alternate adding dry ingredients with grapefruit juice, mixing gently until combined.
  2. Divide the batter evenly into prepared pans. Bake at 325°F until a toothpick inserted in the center comes out with a few moist crumbs. Let layers cool completely before assembling.
  3. Cook sugar, cornstarch, and grapefruit juice until slightly thickened. Temper in egg yolks, return to heat, and cook until thick. Remove from heat, stir in butter, and chill until set.
  4. Beat butter and cream cheese until fluffy. Slowly add powdered sugar, cream, vanilla, and salt. Mix until smooth and creamy.
  5. Place one layer on a plate, spread frosting, then add a ring of frosting around the edge and fill with grapefruit curd. Repeat with remaining layers. Finish with a smooth outer layer of frosting.

Notes

  • I always let ingredients reach room temperature — it makes mixing easier.
  • I cool the cake completely before frosting to prevent melting.
  • I taste the curd before chilling to adjust sweetness if needed.
  • I chill the cake slightly before slicing for cleaner pieces.