I sometimes worry that I might be a witch. It would make sense – I am not totally unsinister, with my weird red hair, beady black eyes, fearsome straight nose and strong Welsh ancestry (full of witches, Wales).

And it would explain a series of terrible things happening to people I hate. Three people, whom I have had cause to dislike intensely, have come to sticky ends – one had a near-fatal heart attack and was then made redundant, another broke their leg in an horrific accident and the other one actually died of cancer. All completely true. All in the last 3 years.

I cannot deny that I wished bad things for all of these people. But at the same time I cannot feel too guilty about any of it, because that would be to acknowledge that I think I really might be a witch – and that question would bring the priest and the doctor in their long coats running over the fields.

And anyway, terrible things happen to people I like, too – for example the woman I know whose newborn suddenly died last week, or my mother-in-law who had to have an emergency operation at Christmas. So if I do have any magical powers of Wicca, it probably isn’t that I bring great pain and suffering to people who cross me – it’s probably just that I bring shitty bad luck to everyone.

It is in this contrite mood that I turn to Celebrate, by Pippa Middleton. Everyone made terrific fun of this book when it came out, so furious were they all that she not only has a marvellous bottom and lovely swingy hair, but that she had landed a £400,000 book deal for writing about how to make paper chains.

But the thing is, this book is really terribly good and very inspiring and completely worth it if you are halfway inclined to throw parties but have, like me, little creative flair. And those famously obvious tips everyone scoffed at are actually perfectly sensible and not so obvious and stupid when you think of the awful, charmless parties you have been to where there’s nowhere to sit, nowhere to put your coat and not enough to eat. If I turned up at any party even half as pretty as the ones shown in the pictures in Celebrate I’d be fucking beside myself with excitement.

So anyone who says this book is no good is just a bitter, miserable sour-face and I hope something awful happens to them.

It’s also full of recipes, which I didn’t realise. They are good, all useful classics like kedgeree, gravadlax and simnel cake and she has some brilliant ideas for inexpensive mass-canapes, like baking tiny baby new potatoes and finishing them off with a blob of sour cream and caviar (she suggests Sevruga, but there is nothing wrong with Lumpfish, frankly). AND she’s got a twice-baked souffle thing, which I’ve been meaning to try for ages.

Pippa has also had the audacity to include a rainbow birthday cake, which caught my eye as it’s Kitty’s birthday quite soon and I do so like to present children with exactly what they want – i.e. hideous plastic toys with flashing light and noises, telly, full-fat, full-sugar, full-salt foodstuffs and enough E-numbers to blast them into space.

I was sceptical about the instructions for this cake, so I thought I would give it a go and possibly fuck it up, just to spread that essential extra bit of bad karma.

But even I didn’t manage to ruin it too badly, although it didn’t turn out anything like the picture. But that’s my own fault. My complaint with this cake is not the method, which would be fine if you were a little more precise, artistic and meticulous than me, but that my blue and green came out as more or less the same colour. I think if I was going to do this again, I would know my limitations and maybe stick to only four colours – two in each sandwich half.

I might even, thinking about it, if I wanted to do four colours per sandwich half, fashion a cardboard cross to sit in the tin so that you could dollop the batter with confidence and whip the card away at the last minute to leave four reasonably even segments of colour.

I am also at a loss as to how one would present this without covering it with some sort of icing, as although the colours come out beautifully on the inside, the outside goes brown during cooking. Pippa helpfully includes a recipe for buttercream icing, which does the job: 125g soft butter, 250g icing sugar, 2 tbsp freshly boiled water and whisk.

The cake itself is delicious and the batter doesn’t suffer too much from having the air knocked out of it when you mix in the food colouring.

Anyway so here we go:

Pippa’s Rainbow Cake

the exact recipe can be found on p.312 of the excellent Celebrate, which I urge you to buy if you have half a mind to.

This mixture makes enough for a 20cm round or 18cm sq cake tin.

200g self-raising flour
200g sugar
200g butter at room temperature
4 eggs !! I know rather a lot
Large pinch of salt

Preheat the oven to 180C.

1 Cream together 200g butter and 200g sugar. Add the salt.

2 Whisk in the four eggs one by one. You do this to stop the mixture from curdling. I must say, I have never managed to stop a cake mixture from curdling completely even when doing this – but at the same time it has never made the cake horrible or anything. Having said all this, best not to dump all four eggs in at the same time.

3 Now fold in the flour.

4 Now divide your cake mixture into as many separate bowls as you have colours and give each bowl its own teaspoon with which to mix in the colour. Add each colour until you are happy with the saturation and then spoon the colours into your (well-greased) tin.

I was worried about this as I assumed they would all merge together and create a hideous grey/brown cake. They do not, as cake batter is reasonably stiff, but a clumsy hand such as mine means that I didn’t get a gorgeously even distribution of colour as someone more talented might have. But these things are all about practice.

3 Give the tin a little shake to even the top out and then bung in the oven for 30-40 mins.

After this has cooled you may find you need to level off the top with a knife in order to be able to sandwich your two halves together, with the prettiest cake bottom (eh? See what I did there??) facing uppermost. As I had buttercream on the outside, I filled the middle with jam.

And I was really very pleased with it. So if Pippa suddenly drops dead of a brain tumour, you will know who to blame.