Melbourne pastry chef Helen Goh, 51, started working for Israeli-British chef Yotam Ottolenghi, 48, soon after moving to London. The two became firm – and occasionally fiery – friends, sharing cultures, children and plenty of cake.

HELEN: We met in 2006, when I relocated to London from Melbourne. Yotam was interviewing me for a job, so he was rather formal, even though we were sitting in the sun on a ledge outside Ottolenghi [his deli/cafe] in Notting Hill.

Yotam hadn't published any cookbooks or started his Guardian newspaper column, so I had no idea what to expect. My husband David, who is Jewish-Australian, warned me not to call him "Yatom", which means "orphan" in Hebrew, so in my head I was going, "Yo-tam, Yo-tam" as we went downstairs to a very busy kitchen.

I'd been a head pastry chef for years, but when I saw these colourful piles of salads everywhere, I just had to learn how to make them. Yotam agreed; he's very easygoing, which is probably why we're still working together.

It was a baptism of fire. I was coming home exhausted, with blisters on my fingers from all the chopping. After four months, I told Yotam I was going to leave to complete my doctorate in psychology. He has a master's in philosophy and comparative literature and was a newspaper section editor, so is used to juggling different lives.

He suggested I manage the smaller Ottolenghi in Kensington, which meant less chopping, and created a job for me called "product development", so I could keep working flexible hours.

Once I brought home a cake and offered a slice to my son Max. He asked if Helen had made it. When I said no, he said, ‘No thank you.’

Part of it was to come up with new ideas, recipes and menu items. A group of us, including Sami Tamimi, Yotam's executive chef, became like family. Yotam and I were always talking about cakes; I'd often pop over to his place on Sundays with cakes I'd baked. I love simple, classical recipes; he nudges me to be bolder.

Our friendship really took off in 2008 when Yotam came with me on a culinary tour of Malaysia, where I'd spent the first 10 years of my life. He's idiosyncratic about food; he wasn't into slimy things like glutinous rice, or rambutans – because of their seeds. I got him to taste a durian, and it repeated on him all day. He met my mother, who flew from Melbourne to meet him, and some of my extended family. There were times when he saw me crying and behaving in a way that he'd never seen before. It was raw, unresolved stuff from my childhood; I cringe now. I was sure he'd want to take a break from me.

Yotam is godfather to my eldest, Sam, who is six, but is just as affectionate with Jude, my two-year-old. We have play dates in the park with the two boys Max, 4, and Flynn, 2, that Yotam has with his husband, Karl. Yotam is an outspoken advocate of surrogacy, and I was a witness to his long, complicated journey to parenthood. Both my sons were medicalised pregnancies; our respective journeys towards having children gave us even more to talk about.

Parenting pressures mean we don't see each other as much as we used to: three more stores have opened since those early days, and Yotam and Karl have moved away from West London, where we both used to live. But we reconnected last year when we began working on our book, Sweet. One early recipe for the book was a traditional Anzac biscuit.When Yotam Instagrammed it, he called it a cookie. I was incensed! His motto is, "Who cares as long as it tastes good?"

YOTAM: When I told my Aussie neighbours I was interviewing Helen, they were like, "Oh my god, in the 1990s she owned this Melbourne café called Mortar & Pestle that had the best cakes ever." Right from the start I was struck by her passion and intensity. Everyone was. My husbandKarl wasmanaging our littleOttolenghi in Kensington, and he'd say, "That Helen is showing those guys in the kitchen what's what!"

She is a perfectionist. She'll get wound up about biscotti that doesn't snap on day three like it did on day one. She's an extremely talented cook but is too uncompromising to be a head chef. Recently, she stormed out of a meeting and when I rang to smooth things over, she hung up on me! Helen can simmer and boil but she is very good at listening and giving advice, especially about the kids. I also talk to her about my aged parents in Jerusalem. Politics aren't her thing; I used to try to explain the situation in the Middle East to her but she would forget in a week and ask me the same questions all over again.

[Executive chef] Sami and I want our dishes to appeal to the eyes as well as the tongue. Helen gets this. In the early days she'd come around for Sunday tastings with these boxes of delights she'd baked; Karl and I would see her coming and groan, anticipating the sugar rushes.

She's contributed recipes to my other books but Sweet is our first book as co-authors. When I told her halfway through working on Sweet that it was all looking too brown, she made every recipe pop with colour. There's a sponge cake in there which, when you cut it, has vertical lines of blackcurrant and lemon butter cream.

When we went to Malaysia, Helen had some tense moments with her family. Her aunt taught me how to make proper tofu: silken, with a crust. And at this incredible market, Helen pushed the limits of how far I'd go with smells and textures: durians weren't as awful as I thought, though they did stay on my breath all day.

Helen and I often bitch about the Brits, who can be very reserved. We've always had an informal relationship. A group of us go over to Helen's each Chinese New Year; she cooks up amazing banquets with fortune cookies whose notes she writes herself.

She also does incredible children's parties. Once I brought home a cake I'd made at work and offered a slice to my son Max. He asked if Helen had made it. When I said no, he said, "No thank you." Our children are all different personalities but they get on well and share a love of food – and fun. Helen and I find intense joy when we're together. It rubs off.

Sweet, by Yotam Ottolenghi and Helen Goh (Penguin Random House, $55), is out now.