Bulgarian Walnut Marble Sponge Cake (Keks) Recipe

This simple yet elegant cake reflects the tradition and heart of Bulgarian baking. Its soft, airy crumb, crunchy walnuts, and hint of cocoa make it perfect for any time of day — served with coffee for breakfast or enjoyed as a light dessert after a meal.

Note: This cake contains no baking powder or baking soda. Its rise comes entirely from the air incorporated into the whipped egg mixture, which gives it a naturally light and delicate texture.

This beloved Bulgarian cake recipe has been lovingly passed down from my mother-in-law, carrying with it the spirit of generations of home bakers. Her mother was a teacher who also knew how to cook — and this recipe, passed from grandmother to mother to daughter, is charged with the warmth of cozy evenings, the smell of colorful autumn leaves, and a deep sense of family history.

Sharing it with me, she wrote:

My mom’s recipe is the taste of home — the delicious flavors of home-cooked meals, a warm hug after a long day, and cherished childhood memories. The soft, flavorful texture with distinct yellow and brown ends and a brownish crust makes every bite unforgettable.

Ingredients

• 80 g (3/4 cup) raw walnuts

• 5 large eggs, room temperature

• Zest of 1 lemon

• 170 g (3/4 cup) granulated sugar

• 12 g (1 tablespoon) water

• 115 g (1/2 cup) sunflower oil (can use avocado or vegetable oil)

• 150 g (1 1/4 cups) all-purpose flour

• 12 g (1 1/2 tablespoon) unsweetened cocoa powder

• powdered sugar for topping

Instructions

1. Prepare the pan:
   Roughly chop the walnuts into six pieces each and spread them evenly across the bottom of a loaf pan (about 20 × 10 cm / 8 × 4 in).

2. Beat the eggs and sugar:
   In a large bowl, combine the eggs, sugar, and water. Using an electric mixer, beat on high speed for about 5 minutes, until the mixture is fluffy, pale yellow, and doubled in size.
   This step is essential for creating volume — it’s what makes the cake rise naturally.

3. Add the oil:
   With the mixer running on medium speed, slowly pour in the sunflower oil in a thin stream. Mix until fully combined.

4. Incorporate the flour:
   Reduce the mixer speed to low and gradually add the flour. Mix just until incorporated — do not overmix.

5. Add the zest:
   Gently fold in the lemon zest using a spatula.

6. Divide the batter:
   Pour about ⅘ of the batter evenly over the walnuts in the prepared pan.

7. Make the cocoa swirl:
   Add the cocoa powder to the remaining ⅕ of the batter and stir gently to combine. Spoon this cocoa batter over the plain batter and swirl lightly with a knife to create a marbled pattern.

8. Bake:
   Bake at 220°C (425°F) for 10 minutes. Without opening the oven door, reduce the temperature to 180°C (350°F) and continue baking for about 35 minutes, or until a toothpick inserted in the center comes out clean.

9. Cool:
   Remove from the oven and let the cake cool in the pan for about 10 minutes. Then transfer to a wire rack to cool completely. Top with powdered sugar, slice, and enjoy!