Todd Wilbur has found himself an intriguing line of work.

Wilbur, 38, is the force behind a series of six “Top Secret Recipe” cookbooks that have sold more than 1.5 million copies.

What started as a lark 20 years ago  trying out a knock-off recipe for Mrs. Fields Cookies that was floating around  has turned into a full-time enterprise. Dissatisfied with the results of that first experiment, Wilbur vowed he could do better. Now he has become America’s premier food sleuth.

Here’s the deal: Wilbur tries to crack the recipes behind some of the favorite dishes and drinks offered by chain restaurants and food producers.

So far, he has decoded the secrets to more than 1,000 items ranging from McDonald’s Big Macs to Girl Scouts Thin Mints to Bailey’s Original Irish Cream liqueur.

The books and Wilbur’s Web site  www.topsecretrecipes.com  are a sensation.

“It’s so fun  there’s nothing else like it,” Wilbur said in a recent telephone interview from New Orleans, where he was taking a break from a publicity tour for his latest book, “Top Secret Recipes: Sodas, Smoothies, Spirits & Shakes.”

“I see people making this stuff at home and freaking out their friends,” he said. “You think you’re not supposed to be able to make KFC cole slaw, but you can make all these products in your kitchen with ingredients from the supermarket.”

Wilbur, who lives in Las Vegas, visited Lawrence earlier this month while in the Kansas City area to promote the top-secret drink book. His first book, “Top Secret Recipes,” came out in 1993.

The new book provides readers with simple, step-by-step instructions to create popular beverages using readily available ingredients. It features recipes for products such as Sonic Cherry Limeade, Starbucks Frozen Frappuccino, Chili’s Margarita Presidente and 7UP soda.

How does he do it?

Call Wilbur’s technique reverse engineering. He knows how a finished product like a Big Mac looks and tastes. So he simply works backward, trying to identify the ingredients and the processes used to create the item.

It takes lots of trial and error in his home kitchen. Some recipes are easy to crack, while others take days or weeks to decipher.

“You bring a product home, taking it apart and making notes about what goes where,” he said. “Then you try to re-create it, building it again from scratch.”

And he does a lot of on-location research into popular dishes and drinks from chain restaurants. Servers can be good sources of information about a menu item.

“They’ll often find out for you what’s in it,” Wilbur said. “Then you just use all your senses  taste it, touch it, smell it and look at it very closely.”

Preparing his latest book was especially fun.

“I was drunk all summer trying to make those signature drinks from the restaurant chains,” he said. “You go in early, watch the bartenders and see what they’re doing.”

Food corporations and restaurant chains don’t seem to mind what he’s doing.

“We haven’t been sued or anything,” he said. “I’m not the only one who clones stuff. The Big Mac is a clone of a Big Boy (hamburger) Â and Pepsi came from Coke.”

And while he usually succeeds, one recipe has Wilbur stumped  Fig Newtons. Other items just aren’t worth the effort.

“There’s been stuff I’ve tossed or never finished,” he said. “I was doing Hormel Chili awhile back. Then I thought, ‘Why do I want to do this? It’s not good chili.’ It wasn’t good enough to clone anyway.”