This legendary cake is the epitome of indulgence—rich, buttery, and infused with the warm, aromatic flavor of rum. The secret to its incredible moistness lies in the technique: a simple, tender cake is baked, then immediately drenched in a hot, buttery rum syrup.
This syrup soaks into every pore of the cake, creating an unbelievably tender texture and deep, complex flavor that only gets better with time. It’s an elegant, foolproof dessert that always impresses a crowd.
The Science of a Soaked Cake & The Perfect Syrup
The magic of this cake is in the soaking syrup. A standard cake cools and firms as it sets; this cake is transformed while still hot from the oven. The hot syrup, a simple mixture of butter, sugar, and rum, is thin enough to penetrate deeply into the cake’s crumb.
The sugar in the syrup hygroscopically attracts and holds moisture, ensuring the cake stays incredibly moist for days. The alcohol in the rum doesn’t fully bake off in the syrup, preserving its distinct flavor, but the high heat mellows any harshness.
Using pudding mix in the batter (a classic trick) adds extra starch and stabilizers, guaranteeing a consistent, fine crumb that can absorb the syrup without becoming mushy.
Ingredients
For the Cake Pan:
- ½ cup (60g) finely chopped walnuts or pecans (optional)
- 1 tablespoon unsalted butter, melted (for greasing)
For the Cake Batter:
- 1 cup (2 sticks / 226g) unsalted butter, softened
- 1 ½ cups (300g) granulated sugar
- 4 large eggs, room temperature
- 1 teaspoon vanilla extract
- 2 ½ cups (313g) all-purpose flour
- 1 (3.4 oz) box instant vanilla pudding mix
- 2 teaspoons baking powder
- ½ teaspoon salt
- ½ cup (120ml) milk
- ½ cup (120ml) dark rum
For the Buttery Rum Soaking Syrup:
- ½ cup (1 stick / 113g) unsalted butter
- 1 cup (200g) granulated sugar
- ¼ cup (60ml) water
- ½ cup (120ml) dark rum
- ¼ teaspoon salt
Instructions
1. Prepare the Bundt Pan: Preheat oven to 325°F (165°C). Generously grease a 10-12 cup Bundt pan with butter (not cooking spray, for best browning). If using nuts, sprinkle them evenly in the bottom of the pan.
2. Make the Cake Batter & Bake: In a large bowl, cream the softened butter and sugar until light and fluffy. Beat in eggs one at a time, then vanilla. In a separate bowl, whisk flour, pudding mix, baking powder, and salt. In a measuring cup, combine milk and ½ cup rum.
Add the dry ingredients to the butter mixture alternately with the rum-milk mixture, beginning and ending with dry. Mix just until combined. Pour batter into the prepared pan and smooth the top. Bake for 55-65 minutes, until a toothpick inserted comes out clean.
3. Prepare the Soaking Syrup: About 10 minutes before the cake is done, make the syrup. In a small saucepan, combine butter, sugar, water, rum, and salt. Bring to a simmer over medium heat, stirring until sugar dissolves. Let simmer gently for 3-4 minutes. Remove from heat.
4. Soak the Hot Cake: As soon as the cake comes out of the oven, leave it in the pan. Immediately and slowly pour about one-third of the hot syrup all over the top of the hot cake. Let it absorb for 2-3 minutes. Repeat with the remaining syrup in two more batches, pausing to let it soak in. You will see the cake absorbing the syrup.
5. Cool Completely in the Pan: Allow the cake to cool completely in the pan on a wire rack, about 2-3 hours. This cooling period is crucial—it lets the syrup fully integrate and the cake structure set.
6. Invert, Glaze & Serve: Once completely cool, run a thin knife around the edges and center tube to loosen. Invert the cake onto a serving plate. The nuts (if used) will create a beautiful top.
For extra shine, you can gently brush any remaining syrup from the pan over the cake. Let sit for at least 4 hours, or ideally overnight, before slicing for the best flavor and texture.
Pro-Tips for the Ultimate Moist & Flavorful Rum Cake
- Use Dark Rum: Dark or spiced rum provides a deeper, more complex flavor than white rum.
- Don’t Skimp on Greasing: Use softened butter and a pastry brush to grease every crevice of the Bundt pan for a flawless release.
- Room Temperature Ingredients: This ensures a smooth, emulsified batter for even baking.
- Syrup Timing: Have the syrup ready just as the cake finishes baking. Pouring it on a hot cake is non-negotiable for proper absorption.
- Patience with Soaking: Pour the syrup slowly in batches—this prevents overflow and ensures deep, even saturation.
- Cool Fully in Pan: Do not attempt to unmold the cake while warm; it needs the structure of the pan to set as it cools and absorbs.
- Make Ahead: This cake tastes best 1-2 days after baking. Wrap it well and store at room temperature.
This Classic Rum Cake is a guaranteed crowd-pleaser that only improves with time.
