Would this be a mean and rotten thing to do?

[Halloweenscream]

I need to take youngest shopping at the weekend for a couple of essential bits he needs.. he's always eyeing up the cakes in the cafe but he never asks just says that they look yummy so I thought I'd treat him to a cake and hot chocolate.

Would it be very mean to leave my teenager at home? I feel guilty even considering it, but honestly I dread going anywhere with eldest. He never wants to do anything with us unless it involves buying him something. He won't want to come out but will if he knows it might involve food. Then he will guzzle down his food as quickly as possible and demand to leave or go and sit in the car because he's bored.

Eldest does get time with us alone too, and gets treated, but I hate to say it he can be a real pain in the neck and acts like a toddler.

I'd ask him if he wants to come shopping, no mention of cake and hot chocolate. he'll inevitably say no.
Go shopping with youngest. Have a lovely chilled out time eating cake and just take teen one home.
You'll be happy, little one will be happy and teen will be happy.

Given the OP, I think it might be. Coffee shops and cafes are expensive, if it's something that can never be afforded, I can understand why op feels guilty. Ours are a little too comfortable in the local Starbucks but if I'd only even taken DS to there or equivalent once of twice in the last few years, I'd be more fussed about leaving a kid out.

OP it's fine to treat them nicely in different ways. But ten a cake to eat in his boy cave

More than ok it's important to spend one to one time with each child. Enjoy your cake

I’m not sure I’d even bother to bring him a cake home.

Ha, probably am overthinking it. Going out to a cake/coffee place is a treat for us as it's not something we do very often. Having said that when eldest was younger he did get treated to eating out a lot more, we're more frugal these days!!

The guilt is probably because I know I'll enjoy a couple of hours with youngest who is so well behaved without the stroppy teen.

I wouldn't think twice about doing this with my two. They each get 1:1 time and know that what we do then is special.

Its normal for a teen to be stroppy. It's fine for you to spend time with one child without the other. As long as you do your best to spend time with your teen then go for it. The way you describe them though sounds a bit off, guzzling in particular stands out to me. One day your youngest will be a teen too. If their only offence is being stroppy then you have done a good job.