A LONG, long time ago, before glorious farmers markets bloomed, before the non-stop Food Network, recipe blogs, celebrity cooks trying not to look foolish on Iron Chef, before the proliferation of excellent food magazines ... and way before every third villa and farm kitchen in France and Italy became a cooking school, I journeyed far to study with Simone Beck in Provence.

What propelled me across the Atlantic in those dim years? My husband was sailing all the time he was not working. My daughter was entranced with her horse. I often felt that I was flying around my room, a bird come in through the chimney. I wanted to be a writer but kept cooking instead. Go somewhere new, I thought.

My friend Jeannette called to tell me about the cooking classes and before she finished the sentence, I said, "Let's go."

We were five at Simone ("Simca") Beck's honey-coloured house, La Campanette, in the hills above Grasse: Jeannette, also from San Francisco, two pretty and accomplished young women from Atlanta, and a woman from South Africa who was sent there while her boyfriend went on vacation with his wife. Jeannette and I had cooked our way through Mastering the Art of French Cooking, which Simca co-authored with Julia Child. We were adept at dinner parties featuring cream soups, veal Prince Orloff, Grand Marnier souffle, and other flamboyant, delicious recipes.

We loved [Beck's 1972 book] Simca's Cuisine, her straightforward approach, and immediately liked her no-nonsense rigour in the kitchen. On the first day she gave each of us an apron that matched her impression of us. Mine was plain blue, while the others got charming flowers and stripes.

Simca was cordial to us, but not friendly. When Cathy from Atlanta asked one question too many, Simca cut her off with "Are we going to measure or are we going to cook?" We worked in the morning, and then enjoyed a sumptuous lunch on the terrace - fish mousseline with hollandaise, pizza with pastry crust, sole in ring mould with veloute, and various sausages in brioche - not exactly Sunday night suppers but still easy and fun. We were assigned small tasks. We took notes. We did not clean up. If one of us asked a question she usually looked incredulous through her tinted glasses and curtly said, "But you have it in de Mastering," as if we should have memorised the whole tome.

But I was learning how to beat egg whites in a copper bowl until I could hold the bowl upside down over my head - that's how you know they're stiff enough. I learned to boil chicken stock uncovered so it reduces and concentrates. We made airy rolled souffle filled with crab. She preferred metal spoons because wooden ones "always have some fat on them". I learned to keep my knives sharp and dry.

Never waste anything. I saw her save the whites when only yolks were needed. Left-over bread became crumbs. Shells of shrimp went into the broth. In that plain kitchen, I acquired life-changing habits. Many small changes add up to revolutionary change. She respected ingredients as a writer respects words. Frugal as she was, the table was set with largesse.

Her trucs and scoldings and care gently seeped into my hands and made me more aware as I stood at the stove. I began to see the process of cooking as an art and a practice, not a means to an end. I began to love the battered pans, wooden bowls, a particular slotted spoon, colanders and baskets. My tools.

French desserts descended to earth from heaven. We constructed then devoured Simca's toffee-based tart of packed-down apples, chocolate gateau garnished with cherries in kirsch, and a dense chocolatey-chocolate mousse without cream.

She taught the French way with meringue - cook it over hot water then, through a pastry tube, pipe decorative rings around fruit or lemon tarts. (Way too much trouble.)

I could not know then that from Simca's dessert repertoire, one recipe would come to stand for all the tastes, aromas and bliss of my time at La Campanette - Le Diabolo, a flat, dense, unassuming chocolate cake. Simca took the recipe from her mother's little black notebook. I recall vividly the first taste: the inner essence of chocolate, sweet, with a touch of almond, and buttery with a slight hit of bitterness from the coffee in the frosting. A complex cake, I thought. I don't know if I've ever made a complex cake before. The ones I knew were straightforward, except for my mother's formidable Lane Cake, which I'd never attempted.

The name, too, is complex. I assumed diabolo meant devil. But a French devil is diable. Italian and Spanish devils are diavolo and diablo. Going way back to the Greek, a diabolos was a liar. For later Christian writers, the word meant "the liar who speaks against God", therefore, a devil. I can see why one might think of that deep chocolate as diabolical, as in the devil made me do it. But why Simca's mother spelled her cake diabolo remains a mystery. Made in a round baking pan, the ancient devil stands 5cm high, at most. Although in her cookbook Simca lists an American chocolate, you can be sure that in her French kitchen she used chocolate from a special shop in Paris. Little flour is called for, and ground almonds keep the batter from ambitious rising. The top becomes slightly crusty and the middle stays moist - more than moist but not quite creamy. As soon as it cools, you pour over it a simple coffee-based chocolate butter cream, thin but intense. Guests put down their forks and look at you as though you've unveiled The Winged Victory. A sliver will do.

Discovering Le Diabolo was sort of like the moment of recognition when you're dressed in blue flounces and someone wearing black Prada walks in. You get it. When something is this good, you don't need much. Sometimes I ring the cake with raspberries, but, really, what's the point?

In my kitchens, I have turned out Le Diabolo on to the same white Wedgwood plate for my daughter's birthdays, endless dinner parties, potlucks, even funerals. Now my daughter bakes it for her family, and I've passed on the recipe to many friends, who, in turn, have handed it to others.

On that first day, however, my history with Le Diabolo was unwritten. I ate each bite slowly, savouring every tender morsel.

In the afternoons, we meandered to Biot, Fayence, Vence. We were allowed in the kitchens of the Michelin-starred chefs in the area. Sharp-eyed Simca took us to markets and taught us to buy the right fish - look at its eyes and the shimmer of the scales - and cunning little cheeses wrapped in grape leaves, and olives, and small purple artichokes.

We learned to drink kir royale (and I'd thought champagne was glamorous) on the terrace at evening, where, with Simca and her husband Jean, we were sometimes joined by Julia Child and her courtly husband Paul.

The effervescent sunset light in the kir seemed to have absorbed the colour of the rays raking across the distant hills. Julia was interested in how we "girls" were getting on. Her high voice thrilled us, and although we were shy around her, we had fun trying to imitate her back in our quarters.

I was seduced by the gentle landscape and by the idea of a life in the countryside. The air was balmy. As we drove, I was dazzled by the golden, perched villages, the Matisse chapel, and the acres of roses cultivated by perfume makers. We sometimes stopped, as evening fell, at a small square and dined outdoors under greening plane trees.

This is an edited extract from Lonely Planet's new A Fork in the Road: Tales of Food, Pleasure & Discovery on the Road edited by James Oseland ($24.99). Frances Mayes's Under Magnolia: A Southern Memoir, is due to be published in 2014.