Harry Potter Spell Book birthday cake

This is my Harry Potter-themed cake for the daughter of one of my colleagues. Chocolate sponge and salted caramel buttercream, with various fondant Potterisms I made…..

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I rarely make novelty/themed cakes as they are not my strength, and there are many out there who are true cake artistes. But I do love a challenge and this is a cake I have made a few times now.

My philosophy with any cake, though, is that flavour must come first.

I have lost count of the number of times I have eaten an artistically jaw-dropping cake that has cost a small fortune, only to experience dry or flavourless (or both!) sponge, sickly icing and very little going for it: that really does make me sad each time.

The cake itself:

The cake itself is a standard all-in-one chocolate Victoria Sponge recipe, scaled up, which takes literally minutes to mix up.

The buttercream:

The buttercream is a fairly standard buttercream into which I mixed some salted caramel and a little melted and cooled dark chocolate.

The buttercream is used to sandwich the two layers together and it acts as the glue for the thin fondant icing that covers the cake.

The decorations:

Fondant icing can be a sickly-sweet affair, with some varieties tasting almost soapy. I like to use quality fondant icings: the Renshaw brand is wonderful and is rolled out thinly to cover the cake.

The items such as the wand, red bookmark and scarf and were very simple to model in flavoured fondant. That said, I often use a plain fondant and flavour it with things such as melted chocolate, lemon juice or zest and the like, depending on what I am going for.

The snitch was cake mixed with a little buttercream, shaped, covered in fondant. Edible gold lustre paint was brushed over the fondant.

Recipe: Harry Potter Spell Book cake

For the cake
  • 350g unsalted butter, softened
  • 350g caster sugar
  • 7 large eggs, at room temperature
  • 300g self-raising flour
  • 50g cocoa powder
  • 3 teaspoons baking powder
For the buttercream:
  • 150g unsalted butter, softened
  • 200g icing sugar
  • 3-4 tablespoons milk
  • 100g dark chocolate, melted and slightly cooled
  • 3-4 tablespoons caramel or salted caramel
To decorate:
  • white fondant icing (about 500g) to cover the cake
  • coloured fondant icing: black, red, yellow….
  • cocoa powder
  • coffee granules dissolved in a little hot water for the writing or edible writing pens
  • gold lustre
  • Harry Potter-themed decorations

(1) Preheat the oven to 160c(fan) and grease and base-line two square or rectangular cake tins, about 25cm by 20cm, and each about 1″ or more deep.

(2) Sieve the flour, cocoa and baking powder together and mix the cake ingredients together gently until just incorporated: don’t over-beat or the gluten in the flour will develop and result in a tougher cake. Divide into the tins and bake for 25-35 minutes until well risen and just coming away from the edges. The surface should also feel springy. Leave to cool in the tins for about 5 minutes before turning out onto wire racks to cool completely.

(3) To make the buttercream, mix the butter, icing sugar and milk until they come together. Whisk for several minutes in an electric mixer until very soft and light:the longer you beat it, the lighter it becomes, almost taking on a moussey texture. Add the cooled melted chocolate and the caramel and beat well for another minute or so. Add more caramel if you feel it needs it.

(4) Remove the greaseproof from the cooled cakes. Lay one cake on top of the other and cut off the edges to give two identically sized cakes: you don’t have trim but I prefer to have the softer edges you then get (and the off-cuts are great to eat, but you can use some of them for the snitch and the hat if you don’t want to use all fondant!).

(5) Roll out four thick strips of black fondant: two a little larger than the width of the cake and two a little larger than the length of the cake: this will give the appearance of the leather book cover. Spoon a little buttercream in the middle of the cake board (which will ensure the cake sticks to the board without sliding around)

(6) Place the bottom layer of cake on the cake board, with the strips just visible under the cake, using a little of the buttercream to ensure it sticks to the board. Spread some of the buttercream on top.

(7) Place the other cake on top. Spread the outside of this sandwiched cake with a thin layer of buttercream:

Shaping and finishing the cake:

(8) Cut out a large V shape, going right up the width of the cake, cutting each side of the centre and cutting almost until you get to the bottom layer of cake. You can make the cut surface a little more rounded and smoother using a sharp knife if you want. It really doesn’t have to look neat at this stage. Spread a little more of the buttercream into the hole: this will give the open book shape, but it looks great just left uncut! NB: it might be easier making the cut on the un-iced cake – I just got a little carried away!  Mind you, the iced cut-out is great to eat as a perk!

(9) Roll out white fondant thinly to a large rectangle, making sure it is large enough to cover the cake and sides: you don’t want it too thick. Pat the fondant down firmly against the buttercream and trim at the base. Brush the top with a little water. You can also place a few very thinly rolled out pieces of fondant, cut into small rectangles around the corners and edges, to start to give the appearance of pages.

(10) Roll out another rectangle of fondant very thinly, this time the same size as the top of the cake and place over the top, patting down gently onto the fondant below. Lift a few corners or edges up a little to give the impression of turned and creased pages, as well as page depth.

(11) Use a sharp knife and make horizontal cuts into the fondant around the edges, trying not to cut through to the cake, although it is not the end of the world if you do! Lightly brush these edges and under the lifted up fondant with cocoa powder, which gives a simple parchment look.

(12) Using a very thin-tipped paint or decorating brush, dip it in the coffee liquid and write or draw whatever you want: I found it easier doing a stroke at a time. Let it dry and brush a little cocoa powder over the top, including the writing. Alternatively, use the edible pens to write.

(13) Decorate with whatever you have to hand.



Author: Philip

Finalist on Britain’s Best Home Cook (BBC Television 2018). Published recipe writer with a love of growing fruit & veg, cooking, teaching and eating good food.

8 thoughts on “Harry Potter Spell Book birthday cake”

    1. thank you Sally. It was very fun to make – and I am such a Harry Potter fan anyhow, that is was even more of a pleasure. I hope your neice enjoys it 🙂


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