Imagine being so good that you get fan letters from Hollywood royalty including Frank Sinatra, Ava Gardner, Lana Turner and actor-turned-president Ronald Reagan.

The recipient wasn’t so much a "who" but a "what," namely, the Hawaiian Happy Cake, formerly offered at the legendary Kemo‘o Farms restaurant.

The Happy Cakes website describes the cakes as giving its consumers mouthfuls of pineapple, macadamia nuts and coconut, just like it did in days gone by.

"Kemo‘o Farms restaurant in Wahiawa was a well-to-do place in the 1950s and ’60s," said Owen O’Callaghan, who bought the recipe, the trademark and related items from the kamaaina Rodby family that owned the restaurant back in the day.

"Charles K.L. Davis used to play there, they had a fantastic chef, and Dick (Rodby, the owner) used to bring in lake trout" from the mainland, O’Callaghan said. "The food was outstanding, there was great Hawaiian music … and in 1967, he started making the Happy Cakes" and registered the trademark, he said.

The restaurant hasn’t been a fancy, white-tablecloth place to dine for years, but the cakes are still being baked by O’Callaghan, an Irish expat who tired of his life as a bond trader in England and moved to Hawaii on Dec. 2, 2002, "the day Linda Lingle became governor," he recalled.

Rodby "kept the cake business" after selling Kemo‘o Farms to a new owner in 1999, but then sold Happy Cakes to O’Callaghan in 2004, he said.

The former bond trader had studied business in college, and "thought it would be exciting to do something entrepreneurial," said O’Callaghan. Contrary to bond-trading, growing and building something from scratch, with ingredients including fresh coconut and locally grown macadamia nuts and pineapple, "is a beautiful thing."

Formerly prepared in the Kemo‘o Farms baking facility, Happy Cakes are now baked in a commercial kitchen in Kaimuki, and come generally in 8-ounce and 16-ounce sizes, though O’Callaghan plans a limited run of 32-ounce cakes that are round with a puka in the center, and come in a gold tin. The smaller sizes are rectangular.

The cakes are dense and moist, and an 8-ounce cake is a good size for two people to share, O’Callaghan said. His recommendation for an accompanying beverage would be either the 100 percent Kona coffee or 100 percent Kona peaberry coffee roasted to Happy Cakes’ specifications and sold under its brand name.

Happy Cakes also sells freeze-dried, instant coffee that is 100 percent Kona-grown, in Holualoa, as are its other coffees.

From 2009 to 2011, the cakes were sold along with other comestibles and potables at O’Callaghan’s Happy Cake Cafe next to Like Like Drive Inn. Now, he sells them at the KCC Farmers’ Market on Saturday mornings as well as via e-commerce through his website.

However, many a longtime customer avails himself of another way to buy their sweet treats: O’Callaghan offers drive-by purchases in Waikiki.

Customers call to arrange a time to meet him, and so they don’t have to hassle with parking, he’ll bring cakes to their cars when they call to say they’ve arrived.

He has customers who have ordered and picked up this way for the past 10 years, because they tell him "it’s not Christmas without a Happy Cake."

"It must be strange to police, around December, to see me run down and pass (cakes) through the window and exchange them for cash," he laughed.

It was posited by your columnist that perhaps the cakes get people as hooked as do other products more commonly purchased in such a manner.

"I think some of them are addicted," he chuckled.

At the KCC Farmers’ Market on Saturdays, the 8-ounce cakes sell for $9.95, while the 16-ounce cakes are sold for $19.95. Pay with a $10 bill or a $20 bill and O’Callaghan will absorb the remaining tax.

The coffees also are sold at the farmers market. The 6-ounce size of 100-percent Kona coffee sells for $12.95, while a 7-ounce bag of the rare, 100-percent Kona peaberry coffee costs $29.95. The coffees also are sold at DFS Galleria in Waikiki on the ground floor, which is open to the public, and at the DFS location in Honolulu Airport.

“Buy Local” runs on Aloha Fridays. Reach Erika Engle at 529-4303, erika@staradvertiser.com, or on Twitter as @erikaengle.