The “Midnight Secret” Christmas Volcano Cake

Byzitouni

“I make this every Christmas and literally have to make it in the dead of the night and then hide it from my family if I want any of it to make it out of the house! Hahaha. Self-control just doesn’t exist when it comes to this stuff!”

If you are looking for a dessert that defines indulgence, this is it. This chocolate cake features a rich, moist sponge with a hidden “volcano” core of creamy white chocolate and a luscious milk chocolate frosting. It’s festive, dramatic, and dangerously delicious.

Why This Cake is a Christmas Essential

  • The Surprise Center: When you slice into it, a thick, velvety white cream core is revealed.
  • Double Chocolate Hit: You get the deep cocoa of the cake paired with a smooth chocolate ganache coating.
  • Make-Ahead Friendly: It actually tastes better after the flavors have melded in the fridge.

Ingredients

The Chocolate Sponge

  • All-Purpose Flour: 2 cups
  • Unsweetened Cocoa Powder: 3/4 cup
  • Sugar: 2 cups
  • Eggs: 2 large (room temperature)
  • Whole Milk: 1 cup
  • Vegetable Oil: 1/2 cup
  • Boiling Water: 1 cup (this is the secret to a moist crumb!)
  • Baking Powder & Baking Soda: 1.5 tsp each
  • Salt: 1 tsp

The “Volcano” White Filling

  • Sweetened Condensed Milk: 1 can (14 oz)
  • Heavy Cream: 1/2 cup
  • White Chocolate Chips: 1/2 cup (melted)
  • Powdered Milk: 3 tbsp (for extra richness)

The Chocolate Silk Frosting

  • Milk Chocolate: 1.5 cups (chopped or chips)
  • Heavy Cream: 3/4 cup

Instructions

1. Bake the Foundation

Preheat your oven to 350°F (175°C). Whisk the dry ingredients, then add eggs, milk, and oil. Once combined, carefully stir in the boiling water (the batter will be thin). Pour into a greased bundt pan or deep round tin and bake for 30–35 minutes. Let it cool completely.

2. Prepare the White Lava

In a saucepan over low heat, combine the condensed milk, heavy cream, and powdered milk. Stir until thickened slightly. Remove from heat and stir in the melted white chocolate. Let this cool to room temperature so it sets into a thick, pourable custard.

3. Fill the Core

If using a bundt cake, simply pour the white filling into the center hole until it reaches the top. If using a standard round cake, use a spoon to hollow out a circular well in the center (don’t go all the way to the bottom!) and fill it with the white cream.

4. Frost with Ganache

Heat the heavy cream until simmering, then pour it over the milk chocolate. Let it sit for 5 minutes, then whisk until glossy. Pour this over the entire cake, allowing it to drip down the sides and “seal” the white center.

5. The “Hide and Seek” Chill

As our recipe contributor suggests, hide this in the back of the fridge for at least 4 hours. This allows the filling to set so it creates that perfect “half-melted” look when sliced.

Serving Tips

  • The “Big Reveal”: Slice the cake at the table to show off the contrasting white and dark layers.
  • Add a Topping: Dust with powdered sugar for a “snowy” effect, or add fresh raspberries to cut through the richness.

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