A truly exceptional plum cake is a masterpiece of holiday baking, distinguished by its deep molasses-like color, intensely fruity flavor, and luxuriously moist crumb. Unlike ordinary fruitcakes, this traditional cake achieves its signature character through three non-negotiable steps: a generous and varied fruit mixture, a crucial soaking process, and the addition of homemade caramel syrup. A great plum cake starts with quality ingredients. The list is long, but each component builds the complex flavor and texture.
- For the Fruit Mix (Soak for at least 24 hours):
- 1 cup black raisins
- 1 cup dried currants
- ½ cup chopped dates
- ½ cup chopped dried figs or prunes
- ½ cup mixed candied citrus peel (orange and lemon)
- ½ cup red glace cherries, halved
- ½ cup chopped almonds or walnuts
- ½ cup brandy, dark rum, or orange juice (for non-alcoholic version)
- For the Caramel Syrup:
- ½ cup granulated sugar
- ¼ cup hot water
- For the Cake Batter:
- 1 ¾ cups all-purpose flour
- 1 teaspoon baking powder
- ½ teaspoon baking soda
- ½ teaspoon salt
- 2 teaspoons ground cinnamon
- ½ teaspoon ground nutmeg
- ¼ teaspoon ground cloves
- 1 cup (2 sticks) unsalted butter, softened
- 1 cup packed dark brown sugar
- 4 large eggs, at room temperature
- 1 teaspoon pure vanilla extract
Stage 1: Prepare the Fruits (Do This 1-3 Days Ahead)
The secret to a moist, non-dry plum cake lies in preparing the fruits. Place all dried fruits and nuts in a large, clean glass jar. Pour your chosen liquid (brandy, rum, or juice) over them. Seal the jar and shake well. Let it sit at room temperature, shaking it occasionally, for a minimum of 24 hours and up to a week. The fruits will plump up magnificently, absorbing the liquid and flavor, which prevents them from drawing moisture from the cake batter during baking.
Stage 2: Make the Caramel Syrup
This step is crucial for the signature dark brown color.
In a heavy-bottomed saucepan, heat the ½ cup of granulated sugar over medium heat. Do not stir, but you can swirl the pan gently.
Watch as the sugar melts and turns a deep amber color. This takes about 5-7 minutes.
Carefully and slowly pour in the ¼ cup of hot water. The mixture will bubble vigorously. Stand back and stir constantly until the caramel is fully dissolved into the water.
Remove from heat and let this syrup cool completely before using. This homemade caramel syrup adds a complex, bittersweet note that sugar alone cannot provide.
Stage 3: Make the Cake Batter and Bake
Preheat and Prep: Preheat your oven to 325°F (160°C). Grease a 9-inch round or loaf pan thoroughly, then line it completely with two layers of parchment paper. This slow, low baking is key for an even bake without burnt edges.
Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and all the spices (cinnamon, nutmeg, cloves). This ensures the leavening agents and spices are evenly distributed.
Cream Butter and Sugar: In a large bowl, using a hand mixer or stand mixer, beat the softened butter and dark brown sugar together for 4-5 minutes until the mixture is very light, pale, and fluffy. This step incorporates air, contributing to the cake’s structure.
Add Wet Ingredients: Beat in the eggs, one at a time, ensuring each is fully incorporated before adding the next. Mix in the vanilla extract, cooled caramel syrup, and black treacle (if using).
Combine and Fold: With the mixer on low, gradually add the flour mixture to the wet ingredients, mixing just until no dry streaks remain. Do not overmix. Using a sturdy spatula, gently fold in the entire soaked fruit-and-nut mixture (including any remaining liquid). The batter will be very thick and dense.
Bake: Spoon the batter into the prepared pan and smooth the top. For even baking and to prevent over-browning, you can wrap the outside of the pan with a layer of brown paper or newspaper secured with kitchen string.
Bake for 1 hour 45 minutes to 2 hours, or until a skewer inserted into the center comes out clean. If the top browns too quickly, tent it loosely with aluminum foil.
Stage 4: The Final, Critical Step: “Feeding” the Cake
A true aged plum cake gets better with time. Once the cake is completely cool, prick the top all over with a skewer. Brush with 1-2 tablespoons of brandy or rum. Wrap the cake tightly in cheesecloth soaked in the same spirit, then in plastic wrap, and finally in foil. Store it in an airtight container in a cool, dark place.
For best flavor: “Feed” the cake with a spoonful of spirit once a week for 2-3 weeks before serving. This process keeps it incredibly moist and intensifies the flavors, creating the ultimate holiday make-ahead dessert.