Since Joanne Fluke launched her culinary mystery series featuring amateur sleuth and baker Hannah Swensen in 2000, she estimates that she’s baked 500,000 of her character’s signature chocolate chip crunch cookies. Whether that’s more impressive than the fact that sales in the series passed the four million mark this year is left for the reader to judge. This March, Kensington will publish her 19th Swenson book, Wedding Cake Murder.

Fluke’s fictional sleuth lives in a small town in Minnesota called Lake Eden and owns the Cookie Jar bakery, a popular community spot known for its unique baked goods and cozy atmosphere. Hannah, a long-single woman who shares an apartment with her sister, will finally get married in the new book, an event that Fluke’s many fans have looked forward to for years. In keeping with the author’s page-turning formula, Hannah helps the local police solve a murder.

You could say Fluke, who hails from generations of bakers, was destined to become a master at the craft. “My grandmother, who lived with us in Swanville, Minn., and my mother were both bakers,” Fluke says while we dine at a charming French café in the San Fernando Valley. “In the winter they baked every single day to warm up the kitchen, and my bedroom was just above the kitchen. I’d wake up to the aroma of cinnamon and chocolate; those wonderful baking smells came through the heating vent in my room.” It wasn’t long before a preteen Fluke started learning how to bake.

Fluke’s grandmother came to America from Germany at the turn of the 20th century when she was nine. She was sponsored by a wealthy American family in Duluth to work as a servant, but the family sent her to school and gave her the pet name Pie Girl. “She was in charge of rolling out the pie crust,” Fluke says, smiling, “and she became very good friends with the pastry chef. She watched and learned, and ended up with dozens of recipes—but nobody ever wrote anything down.” Years later, Fluke and her mother ganged up on Fluke’s grandmother and asked her for the precise amounts of each ingredient in a recipe. “We asked, ‘How much flour?’ And she said, ‘I don’t know—until it’s right.’ ” Eventually they stood watch with a measuring cup and notebook while she made a jelly roll. “My grandmother always scooped out flour with her hand. Mom held a big bowl and would direct my grandmother to dump the flour, or sugar, into the measuring cup. The bowl caught the overspill. I stood by to write down the measurements, and that’s how we learned how to make all her recipes.”

Fluke’s fans have benefitted from this effort many times over. Fluke became a superb baker and cook and now includes 25 original recipes in each Hannah Swenson book. In Wedding Cake Murder, for instance, readers are treated to recipes for Magic White Chocolate Soufflé, Double Rainbow Swirl Cake, Green Tomatillo Stew, and Peanut Butter Potato Chip Cookies. “I have shoe boxes filled with recipes,” Fluke says. “Some came from my family, a lot of them I make up myself, and others are sent in by fans. I bake a couple of times a week, although when I’m testing recipes, it’s a baking marathon. Sometimes my recipes work out beautifully, and sometimes I have colossal failures.” Fluke has a double oven in the kitchen of her suburban Los Angeles home. She considered purchasing a commercial oven, but the room wasn’t big enough for such an enormous appliance.

Writing came to Fluke early on. “When I was in second grade my mother read to me every night,” she says. “There was one particular book—and I can’t remember its title—where for several weeks she read me a chapter each night, until the book was over. When she asked me if I’d enjoyed it, I said, ‘I didn’t like the ending.’ So she told me to write a new one. It took three months, but I did it. When my mother read it she said, ‘Oh, Joey—I like yours so much better.’ And that was it. I started writing.”

Fluke’s first books were suspense novels, and Dell began publishing them in 1980. She moved over to Simon & Schuster in 1987 for three additional thrillers. It was there she met John Scognamiglio, and when he became editor-in-chief at Kensington, it seemed a natural transition for Fluke to sign with him in 1993; she’s been at Kensington ever since.

The versatile Fluke then wrote horror novels for teens under the pen name Jo Gibson (Gibson is her maiden name). “Kensington didn’t want them associated with my adult books, so they asked me to use a pseudonym, which made sense.” She wrote traditional Regency romances as Kathryn Kirkwood and two contemporary romances as Gina Jackson, before finally introducing Hannah in Chocolate Chip Cookie Murder in 2000. Now there are thousands of “Hannahmaniacs” all around the country, and the Hallmark Channel has produced two TV movies based on Fluke’s books. A third, Peach Cobbler Murder, just aired on January 10.

“My mother is the only 20-year overnight success,” says John Fluke, the author’s son, who serves as her manager when he’s not busy running his product-placement TV-advertising company in Los Angeles. “I’m trying to place her books in the Hannah movies, which would be fun for her fans.” A baker like his mother, he’s responsible for creating the variations on Hannah’s “whippersnapper” cookies and contributes his own recipes to the books. Fluke has another biological son and daughter, in addition to her late husband’s three children, whom she considers her own as well; she is the proud grandmother of nine.

Kensington also published Joanne Fluke’s Lake Eden Cookbook: Hannah Swensen’s Recipes from the Cookie Jar in 2011; it made the New York Times Bestselling Cookbooks list, and it has since sold more than 130,000 copies in various formats. But when asked about opening a chain of Cookie Jar bakeries, Fluke replies with a resounding no. “I know how much work it is to own any kind of restaurant or food-related business,” she says. “I don’t hold the copyright to the name, so when people have asked my permission to use it for their own bakeries, I just tell them it would be fine. And if they want to use some of the recipes, I say yes, providing they give credit to the Hannah book it’s in, and if they could sell copies of the books there that would be even better.” Despite this, she doesn’t follow up on any of the requests.

The Hannah Swensen books are cozy mysteries, and Fluke feels a true kinship with her fans. “I’m lucky I write what I do, because my readers are all so nice,” she says. “If I’d remained a thriller writer, the fans might not be that pleasant. You’re going to get some people who are a little... strange. My fans are so lovely.” Fluke is very popular at indie mystery bookstores and libraries. “Some of them have very active Friends of the Libraries organizations, and I often draw up to 150 people at those events.” She usually participates in the Romantic Times conventions; two years ago she rode a float at a meeting in New Orleans.

Fluke, with her flowing blond hair and pretty face, declines to reveal her age when asked. “My mother always said that a lady never tells her age,” she says with a grin. “I’m not sure that I qualify for the lady part, but let’s just say that I do get a discount when I eat at a chain restaurant.”

Some of Fluke’s fans think she’s a lot like Hannah. “That’s mostly because I bake, create original recipes, and love to eat,” she says. “But Hannah can think up great comments on the spur of the moment. I can’t. If someone says something nasty to me at a party, I don’t think of the perfect comeback until it’s too late and I’m on the way home.” Fluke distances herself from Hannah while writing. “I don’t feel that I’m her. I feel much more like I’m Hannah’s biographer, and she’s my best friend.”

Waking daily at 4 a.m. to write, Fluke rarely takes a day off. “The outline for the next Hannah book is already written, but first I have to do my little Christmas book for Kensington,” she says. “They thought rather than be part of an anthology I should do a Christmas story that would be a small book of its own. It will be published next year.” In addition, Fluke’s thrillers from the 1980s are being reissued, which required a lot of rewriting. “I had to bring them up to cultural speed,” she says.

But when all is said and done, Fluke’s heart belongs to Hannah, even though she claims the beloved character is responsible for making Fluke put on weight. “I’ve gained 30 pounds since I started writing the series,” Fluke says. “And I wonder, which title put on how many pounds? Baking half a million chocolate chip crunch cookies was important because I gave so many people my favorite sweet treat.” But she notes that taste testing every batch, to make sure it’s perfect, has certainly had its impact on her waistline.