The Kenyan-born, British-raised, Japanese-based runner heaped praise on the course after finishing second in the Bupa London 10,000 road race held last Monday.
Writing on her blog she said: "It was great to be part of this new exciting race, especially because it was on the proposed course for the London 2012 Olympic marathon.
"I love racing in London because you run along famous streets that are normally full of traffic, and the crowds are always so supportive, even when the weather is terrible as it was last Monday.
"You also get to see London’s historic landmarks such as Big Ben, St Paul’s Cathedral and the fabulous London Eye – a whirlwind sight-seeing tour from a perspective you would never otherwise see."
But she revealed there is another reason why she enjoyed the course so much.
Yamauchi wrote: "The course also took us right past a branch of Ben’s Cookies - makers of the best cookies in the world!
"I don’t have many cookies these days and I must say it was hard running right past their front door with the smell of freshly-baked cookies wafting past us!
"I’ll make sure I stop off for a Ben’s Cookie or two on my next trip to the UK after the Olympics!"
Yamauchi, currently on a sabbatical from her job at Foreign Office while she pursues her Olympics ambitions, is set to be Britain's best hope of a medal in the marathon in Beijing if Paula Radcliffe fails to recover from injury in time.
Yamauchi, formerly known as Mara Myers before she married her Japanese husband, won the Osaka Marathon in January in a personal best of 2 hours 25min 10sec.
She is currently training at altitude in St Moritz but hopes to go home to Tokyo to complete her preparations for Beijing.
To read Yamauchi's blog click here.