Scaling up a cake recipe - any baking gurus can advise?

[WoolyMammoth55]

Hi all,

DS has his 6th birthday party on Sunday and I need to make a carrot cake per his request.

I'm a non-baker! But my MIL has sent this recipe which she thinks is a crowd-pleaser: https://www.bbcgoodfood.com/recipes/frosted-carrot-squares

My question is: this recipe specifies an 18cm square baking tray. The party is outdoors - so they'll be running around and hungry! - and I've got 25 kids coming. I think the little tray would serve maybe 8 of them!

I have borrowed a 30cm x 30cm baking tray from my lovely neighbour. My maths says that the square cm area of this is 3 times bigger than the 18cm one specified in the recipe (30 x 30 = 900cm sq; 18 x 18 = 324).

So if I triple all the quantities, will the cake still work?

And what effect does it have on the cooking time?

Lastly, I've got a nut/seed allergy sufferer coming so I have to replace the sunflower oil... Would melted butter be ok? Anything else that would be better?

Thanks so much for any thoughts or advice :)

I'd do two in the time size in the recipe

I'd triple it and freeze any leftovers in slices. My kids used to love that.

I would do two because the middle might not be as well cooked if you do the larger cake. I don't like the tatse of sunflower oil in carrot cake and always use light olive oil.

Can't help with the quantity question, but use a different oil. Melted butter won't work as it doesn't flow and lubricate like an oil.

I’d go for 3 x the amount as you suggest (well, actually I’d be very particular and go for 2.78 x the amount but that’s probably not really necessary!). Then I’d expect it to take longer baking, but not sure how much longer. It’s going to be a similar thickness to the original so it won’t be much much longer. Maybe 1.3 times the original and then check, then maybe longer?
don’t forget to do extra frosting too!

And I’d also use a light olive oil.

I've got a great carrot cake recipe that is made in a 30cm x 20cm tin.
I'm at work but can post it tomorrow. It's delicious!

Thanks @Talipesmum - part of the recipe is 2 eggs so I thought scaling up everything up by 3x was easier than working out 2.78 of an egg! :)

@Blueuggboots That would be awesome, thank you!

Yup that’s where my fruitless accuracy always falls down 😂😂

Here you go....

And the last one in close up....

@Blueuggboots SO KIND OF YOU! Thank you Xx

No problem! It's a well used recipe hence the bits all over the pages! Hope you can read the measurements if you don't have cups.

Hello, fellow cooking enthusiasts! Recently, I've found myself intrigued by the world of measurements used in our kitchens. One question that piqued my interest was how many tablespoons are in 3/4 of a cup? It turns out, there are 12 tablespoons in 3/4 cup! It's pretty fascinating, isn't it? This can be incredibly helpful when you're trying to follow a recipe but don't have a 3/4 cup measure. I found this information on a wonderful website that offers a wealth of knowledge on various volume conversions. If you're curious, you can check it out here. I hope you find this as intriguing and helpful as I did!

I wouldn't go substituting sunflower oil for a nut/seed allergy sufferer without discussing with their parents first, whether they avoid sunflower or not, and if they do, what do they find useful instead. Straight "vegetable oil" - often rapeseed based - could be fine for example.

Anyway, good luck with the baking and I hope it goes really well!

I'm not so sure about the tablespoon conversions; it will depend a lot on whether you are using level or rounded or heaped tablespoons... (and then also whether you are using 15 mL or 20 mL tablespoons but perhaps I shouldn't scare anyone with that ....)