“You’re putting SALT in the SUGAR jar! THAT’S your great plan?”

Jess sighed and rolled her eyes. “Think about it. We get the robot to help us make some cakes for Olivia’s party, except he uses salt instead of sugar. They’ll be DISGUSTING! One of Olivia’s princessy friends might even be SICK!”

It was the happiest I’d seen my sister all week.

“There’ll definitely be complaints. We just need to make sure Mum knows it was Robin who made the cakes. If it looks like he nearly poisoned half the class, she’ll send him back to Grandma for sure!”

I felt a smile spread slowly across my lips. “This isn’t easy for me to admit,” I told her, “but sometimes, sis … you’re a genius! In a scary, really evil, taking-over-the-world kind of way.”

Robin put on Dad’s apron to bake the cakes. He was still wearing Grandma’s coat underneath, skating round the kitchen like Father Christmas on ice! I noticed he was making a strange noise while he worked.

“Is that … singing?”

“My database informs me that people often sing while completing a task that makes them happy,” said Robin. “I am enjoying baking with you, so I thought it would be appropriate to express my happiness through the medium of song.”

“Please don’t,” said Jess. “It’s really annoying.”

The robot apologized, and I felt a bit sorry for him.

Making the cakes wasn’t actually as bad as I expected. Robin had the recipe in his head, so me and Jess just weighed out ingredients while the robot stirred them all together in a big bowl. Before he started, Robin unscrewed one of his hands and replaced it with an attachment like you get on a food mixer. Watching him remove his own hand was kind of gross but also strangely cool. The best part was we didn’t have to get arm ache trying to stir the mixture. The robot just put his new mixer hand in the bowl and whirrrrrrrrrr! – off it went! It was kind of impressive.

I realized I was actually quite enjoying myself – not that I was about to start singing or anything outrageous like that, but it was a good laugh baking with Robin. When he offered to let us taste the mixture, I almost said yes, until I remembered we’d used SALT instead of SUGAR. It was kind of disappointing because I reckon if we’d used the right ingredients, Robin’s cakes would have been amazing.

Mum came home just as we were taking the cakes out of the oven.

“I popped in to change before I start my shift at the pub,” she said, dumping her bag on the kitchen table. “Those cakes smell amazing!”

“It was ALL Robin,” said Jess. “He did ALL the work so he should take ALL the credit!”

“Oh, that’s very kind of you, Miss Jess, but I’d say it was a team effort.” The robot slid the freshly baked muffins on to a cooling rack. “Would you like to try one, ma’am?”

“I shouldn’t really,” said Mum, drooling already. “They’re for Olivia’s party. But they do smell delicious. Maybe I should sample one – just to make sure they’re OK?”

An evil gleam flickered in my sister’s eyes.

“Anyone else?” said Mum, reaching for a muffin.

“Maybe later,” said Jess.

“I’m not really in a cake mood,” I lied.

Mum took a bite. I stepped back out of range. If Jess was right, that mouthful would come flying back out at any moment.

I watched Mum’s face, waiting for a cough, a cry of horror, as she tasted salt where there should have been sugar.

“Mmmmm!” said Mum, closing her eyes. “This is AMAZING! Robin, you’re a genius!”

Me and Jess exchanged a puzzled look.

“I’m very glad you like it,” said Robin. “However, I was wondering – would you like me to do an inventory of your ingredients?”

Mum frowned.

“While we were baking, I noticed the jar marked SUGAR actually contained SALT!” said Robin. “My sensors detected the mistake before any damage was done, but I’d be happy to run a diagnostic check on all your food-storage units.” He smiled but his eyes swung round towards me and Jess as he said it – like he knew what we’d tried to do!

“That must have been me!” said Mum. “I’ve been so tired lately. Thank goodness you were here to spot it, Robin!”

Yeah, lucky us!

“That went well,” I muttered as Mum headed for the door. “Now Mum thinks she’s found her very own Bake Off champion, it’s going to be even harder to get rid of him.”

“Oh, shut up!” said Jess and stomped off upstairs.