How Happy Crumb Bakery has risen from domestic kitchen hustle to a fast-growing cookie business with the support of Mission Kitchen

Little more than a year ago, Happy Crumb Bakery was a small-scale baking side hustle operating from Grant Marshall-Koper’s home kitchen. Today, the business produces hundreds of cookies each week at New Covent Garden Market, supplies wholesale customers, runs busy, weekly market stalls across London and is about to launch a new corporate experience designed to share its expertise with professional and domestic chefs alike.

Like many Mission Kitchen members, Grant’s journey into commercial baking has been anything but conventional. Prior to making the leap, he spent more than a decade working in the performing arts. "I trained in musical theatre and performed for probably 10 or 12 years," he explains. His stage career included musical revues, cruise ship stints, a long-running show in the Canary Islands and a traditional British music hall production in Sheerness.

He continues to write, but like many performers, the impact of the Covid pandemic prompted a change of mindset. "When Covid hit, I moved into theatre management, and while I was managing I started a little side hustle at home," he recalls.

That side hustle was to become Happy Crumb Bakery. It survived disaster when Grant’s kitchen flooded and was unusable for six months, with the silver lining being it forced the change of direction that brought Mission Kitchen into play and created genuine momentum. “I restarted the business in the summer of 2025 with renewed focus, taking products directly to consumers through local markets,” he says.

The growth was rapid. By October he had left his theatre management role to focus on Happy Crumb full-time.

Finding a home

Grant first heard about Mission Kitchen through a friend who already worked with a business based there. "They said ‘have a look because it might be a really good fit for you’. The recommendation has been transformational.” Mission Kitchen's flexible workspace model allowed Happy Crumb to grow quickly, but at its own speed, initially renting shared space for set time periods, before progressing to its own dedicated production bay, which now serves as the team’s permanent base.

The difference between baking at home and operating in a professional environment was immediate. "At home, I could make 24 cookies in one go and that would take me a couple of hours. In an hour here, I can make maybe 150," Grant says.

That increase in efficiency completely changes the business's outlook and, of course, its potential. "When I started working the local markets, it would take me a week to prepare for one day's worth of sales. It was never going to work at home long term.”

Just as important has been the collaborative nature of the community at Mission Kitchen.

He describes a culture where businesses share knowledge, techniques and ideas, creating an environment that accelerates learning and innovation. "I've definitely become a better cook and a better baker from being here, just from being surrounded by other talented people.

"You pick up tips and all sorts of tricks and techniques and ways of working that you just wouldn't have considered."

Smart cookie

Remarkably, Grant had no formal culinary training. Instead, his baking knowledge came from family. "My nan was a really good baker and I learnt techniques and things from her and my mum. I'm completely self-taught," he admits. He obviously has the skills , as what began as experimenting at home soon developed wings.

He chose to produce cookies because, practically, they travelled well and could withstand courier delivery better than more fragile baked products. Over time, he developed his own dough recipe that forms the basis for his unique range. And the final sprinkle of genius was to make traditional dessert favourites the focal point of his equally unique cookie flavour profile.

While London's food scene is fairly crowded with cookie brands, Happy Crumb has created its own space by deliberately avoiding the flavour combinations commonly found elsewhere. “You won't find a Kinder Bueno or a Biscoff cookie, although I’m definitely partial to those flavours myself,” Grant laughs. “Among the flavours we’ve developed so far are carrot cake, tiramisu, bread and butter pudding, cherry Bakewell and sticky toffee pudding. Far and away the most successful to date has been our apple crumble cookie, which combines cinnamon dough, apple puree and real apple pieces. It’s got a real following - there was uproar when we took it off the menu for a little while!”

Building a brand

Retail markets have been central to Happy Crumb's early success. Today the bakery regularly trades at Lower Marsh in Waterloo, Sydenham Market and Croydon's historic Surrey Street Market, while also attending larger seasonal events and festivals. For Grant, these markets serve a purpose beyond sales.

"The markets are essentially our storefront," he says. The strategy is working. Popular locations regularly sell out, generating both revenue and brand awareness. For Sydenham alone, the bakery prepares around 500 cookies every week and routinely sells every one. Larger events have produced even bigger results.

Growing beyond retail

Happy Crumb has expanded beyond market trading. Those face-to-face interactions help drive online sales, corporate orders and wholesale enquiries through word of mouth and repeat custom. Cookies are increasingly being sold wholesale to cafés and hospitality businesses, on subscription to corporate customers who treat their staff to them, and as branded corporate orders, which have become particularly popular within London's theatre sector, where it all started for Grant.

The connections he and his husband have in theatreland are bearing fruit, as many West End productions are ordering customised cookies featuring show branding for opening nights and press events.

The next major development is the launch of the Cookie Lab, an interactive team-building experience hosted at Mission Kitchen. Participants will learn how to make New York-style cookies, develop original flavours and create their own concepts and branding before presenting them to colleagues. One of the most common questions customers ask is how Happy Crumb creates its famously thick cookies. The Cookie Lab finally reveals this secret.

In October 2026, Grant also introduced Crumb Supply, a dedicated wholesale brand for cookies and desserts.

Market base

Being based at Mission Kitchen places Happy Crumb at the heart of New Covent Garden Market, which offers myriad opportunities.

Grant says the location of Mission Kitchen has provided significant advantages. "It's fantastic. Really, really well connected," he adds.

The bakery's proximity to Waterloo means freshly baked products can be transported almost immediately after production to the market there. "We pick up the cookies and 10 minutes after they've come out of the oven, they're on the stall down there. But beyond logistics, New Covent Garden Market offers us future opportunities for sourcing ingredients and building commercial relationships with traders and foodservice businesses operating across the site.

As Happy Crumb also experiments with new product lines, including fruit-based tarts and wholesale pastry products, those connections could become increasingly valuable.

Longer term, physical retail remains firmly on the agenda – “maybe a shop or a unit of some kind”, muses Grant. Whatever form the next stage takes, he remains clear about the role Mission Kitchen has played in getting the business to where it is today.

"Would we have got to where we are without them? Almost certainly not."

Judging by the fervent desire for Happy Crumb's apple crumble cookies, London's appetite for the company's next chapter is going to keep Grant busy for a good while to come.