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Chocolate Olive Oil Sheet Cake with Milk Chocolate German Buttercream

  • Author: Erin Clarkson
  • Yield: Makes one 9” x 12” cake - serves 12-16 people 1x


Chocolate Olive Oil Sheet Cake with Milk Chocolate German Buttercream



Chocolate Olive Oil Cake

  • 375g all-purpose flour
  • 350g sugar
  • 120g dutch cocoa
  • 2 tsp espresso powder
  • 1 tsp salt
  • 1 ½ tsp baking soda
  • 2 tsp baking powder
  • 4 eggs, at room temperature
  • 1 ½ tsp vanilla
  • 180g Filippo Berio Robusto Extra Virgin Olive Oil
  • 330g whole milk, at room temperature
  • 300g freshly boiled water

Milk Chocolate German Buttercream

  • 110g sugar
  • 12g (1 ½ Tbsp) cornstarch
  • 1 egg
  • 1 egg yolk
  • 1 tsp kosher salt
  • 190g whole milk
  • 1 tsp vanilla bean paste
  • 340g (3 sticks) unsalted butter, at room temperature
  • 180g good quality milk chocolate, melted and cooled slightly



  1. Preheat the oven to 350°f / 180°c. Lightly spray a 9”x13” baking pan with baking spray, and line with parchment paper. Set aside.
  2. In a large bowl, whisk together the flour, sugar, cocoa, espresso powder, salt, baking soda, and baking powder. Add the eggs, vanilla bean paste, Filippo Berio Robusto Extra Virgin Olive Oil, and milk, and mix to combine well. Add the boiling water and whisk until incorporated.
  3. Transfer the batter into the prepared pan, and tap a few times on a flat surface to remove any excess bubbles.
  4. Bake the cake for 40-45 minutes, until the centre springs back, or a cake tester inserted in the middle of the cake comes out cleanly.
  5. Cool in the pan completely.


  1. In a bowl, whisk together the sugar, corn starch, egg, egg yolk and salt. In a medium saucepan, heat the milk and vanilla to just shy of a simmer.  Remove from the heat.
  2. Using one hand to whisk constantly, pour half of the hot milk mixture into the egg mixture. This helps to temper the eggs and stop them from scrambling. Whisk until incorporated, and then pour the whole lot back into the saucepan.
  3. Heat the milk and egg mixture over medium heat, whisking constantly, until it begins to bubble. It will thicken quickly. Once it has thickened, cook for one minute, then remove from the heat. Pour into a shallow container or bowl of a stand mixer and press some plastic wrap over the surface to avoid a skin from forming. Refrigerate until cold - at least four hours, preferably overnight. If you need to speed this process up, you can place the pastry cream in a bowl, then place the bowl in an ice bath. Stir frequently.
  4. Fit your mixer with the whisk attachment, and place the pastry cream in the bowl. Whip the mixture on medium until creamy and lump-free. Begin adding the butter, a few cubes at a time, until fully incorporated. It may look curdled at some point but just keep whipping - it will come together! Once the buttercream is homogenous, add the cooled melted milk chocolate and mix to incorporate.


  1. Transfer the cake to a serving plate or board. Dump the milk chocolate buttercream onto the cake, and, using an offset spatula, spread over the cake, creating swirls in the buttercream. Add sprinkles if desired.
  2. Store leftovers in an airtight container in the fridge.