Giant Oreo Cookie Cake

As most of you may know, I changed jobs recently. My lovely colleagues bought me an amazing cake stand and I also got this really cool giant cookie mould! (Thank you Kate!!) I've had my eye on it for a while so was really pleased when I was presented with it. If you don't already know, I love oreos and baking with oreos so I was really excited to make a giant oreo cookie! It really is more like a chocolate cake with buttercream frosting but it looks like a giant cookie. The texture is dense and chocolatey and it holds its shape really well. I was a bit worried it would not look like the picture!
I used the recipe from Williams Sonoma and found it far too sweet for my liking even though I reduced the sugar amount slightly. I've included the original amounts below as you may have a super sweet tooth but I would recommend 1/3 reduction if you prefer it less sweet.
PS apologies for the last two photos, I had to take it with my phone whilst at work after it was sliced.

 giant cookie mould 

Williams Sonoma Giant Oreo Cookie Cake 

For the cake

45g cocoa powder, plus more for dusting 

200g chocolate, broken into pieces

200g unsalted butter, cut into cubes

125g flour

1 teaspoon baking powder

3/4 teaspoon salt

390g sugar

4 eggs

1 3/4 teaspoon vanilla extract

For the buttercream frosting

560g icing sugar

325g unsalted butter

3.5 tablespoons milk, plus more if needed

1.5 teaspoon vanilla extract

pinch of salt

• Preheat the oven to 180C. 
• Using a small pastry brush, grease 2 sandwich cookie cake pans with butter, making sure to coat all the details and crevices in the pans.
• Dust thoroughly with cocoa powder and tap out any excess.
• To make the cake, melt the chocolate in a heatproof bowl over a pan of barely simmering water. 
• Remove from the heat and stir in the butter, a few pieces at a time, until blended. 
• Let the chocolate mixture cool slightly. 
• In a bowl, whisk together the flour, cocoa powder, baking powder and salt until combined and set aside. 
• Ina  large bowl, whisk the sugar, eggs and vanilla until well combined.
• Add the chocolate mixture and whisk until incorporated. 
• Whisk in the flour mixture until combined. 
• Divide the batter evenly between the pans and spread evenly.
• Gently tap the pans on the counter to release any air bubbles. 
• Bake until the tops of the cakes are shiny and a skewer inserted into the centre comes out with a few crumbs attached, about 35 minutes. 
• Transfer the pans to a wire rack and allow to cool for 15 minutes before inverting the cake onto a cutting board/work surface. 
• To make the buttercream frosting - in the bowl of an electric mixer fitted with the flat beater, combine the icing sugar, butter, milk, vanilla and salt and beat on low speed for about 1 minutes. 
• Increase the speed to medium and beat until fluffy, about 3 minutes. 
• If the frosting is dry, add more milk, 1 teaspoon at a time until it is creamy but still holds peaks.
• Using a large spatula, carefully turn 1 cake over the the printed side faces down. 
• Spread the buttercream evenly over the flat side of the cake. 
• Place the second cake, printed side up on top.