THE EXCITEMENT of dining and staying at the three-star auberge of chef Roger Verge is that each time you go, his creative mind is working out new ideas, new inventions, and exploring new gastranomic paths in every conceivable direction. Verge's beautiful and extraordinary Moulin de Mougins, the old watermill of the village of Mougins, is in the perfumed Provencal countryside behind Cannes.

At the stoves in his kitchen and at his menu-writing table, Verge never stands still for a moment. Every time you visit, almost everything is different.

When he was a boy, Verge wanted to become not a cook but an airman so he could see the world. When he graduated instead as a top cook, he used his cullinary skills to get jobs in many foreign places and was away from France for almost 15 years.

What he learned about far-off cuisines has permanently influenced his own cooking. Now that he is successful, he closes his restaurant for several weeks each year, so he and his wife, Denise, can study the interesting, off-beat cuisines of out-of-the-way places.

That was how they came to Martinique and how Verge discovered the magnificent plantation rums of that exotic, sun-soaked fruit- and sugar-filled island. He discusses it in his new book, "My Cuisine of the Sun," just out in France and to be published in English in the United States early next year.

To quote from the book: "There are two kinds of rum -- one is the pure product of the distillation of the fresh juice of sugar cane; the other is the industrial product made from molasses, which is a by-product from the manufacture of sugar. This second type is colored, not by aging, but by the addition of burnt sugar. But the lovely amber color of the great, pure rums . . . comes from years of aging in oak barrels, exactly like the best cognacs and armagnacs."

Verge left Martinique with many new impressions and several bottles of rare old rum and returned to Paris to work on new desserts.

He called his first invention "Torment of Love." Vegas first perfected a pie crust pastry (a French "paste sablee") made with rum. It is one of the best pie shells ever conceived. It can be used for anything -- including a bacon and cheese quiche.

It's hard to make it in one-pie quantity, so the recipe below is for three pie shells. Divide it, while it is still soft, into separate balls of about 7 ounces (200 grams) each and wrap each separately in foil or plastic. One ball is about right for one pie, and the dough will keep at least a couple of weeks in the refrigerator or a couple of months in the freezer. This dough is a useful staple to have on hand.

Verge then worked out a Martinique-style dessert tart filling of coconut, eggs, rum and vanilla sugar. This dessert tart has an extraordinary, near-perfect balance of aromatic and sweet flavors, of chewy and sensuously velvety textures. You will love it so much that you will finish it quickly, and then will be in a state of torment until you can make the next one -- always, of course, with one of the great plantation rums of Martinique. o

Incidentally, although "My Cuisine of the Sun" will not be published in English until next year, a limited number of copies of the French edition are available by mail from Quinion Books, 541 Hudson St., New York, N.Y. 10014, for $26.15, postage paid. ROGER VERGE'S COCONUT AND RUM TART (Three pie shells and filling for one 8-inch tart) For the rum pastry: 2 cups plus 3 tablespoons all-purpose flour 1/4 cup powdered almonds 5 tablespoons superfine sugar Finely minced outer skin of half lemon 1 pinch salt 13 1/2 tablespoons cold, unsalted butter cut into dollops 2 large egg yolks French Martinique plantation rum Extra flour for flouring pastry board For the filling: Flour for the pastry board 1/3 cup flaked or grated coconut meat 1/3 cup vanilla sugar (see WORKING NOTES at end of recipe) or, alternately, plain superfine sugar with 1 teaspoon pure vanilla extract 1 or 2 pinches powdered cinnamon 3 whole eggs 1/2 cup heavy cream 1/3 cup French Martinique plantation rum

Kitchen Equipment: Ideally, a good food processor; second choice, and electric beater-mixer; or by hand, a large mixing bowl, with wooden spatulas and spoons. Also, a marble plastic or wooden pastry board; rolling pin; pastry knife; cellophane bags to wrap pastry balls; mixing bowls for filling; balloon wire whisk; 8-inch tart baking pan; large fork for pricking; small frying pan; small sharp knife.

Average Time Required Pastry works much more easily if made the day before (it takes about 20 minutes) and left in the refrigerator overnight. Next day, about 20 minutes to roll out tart shell and mix filling. Finally, about 25 minutes in oven.

Fill the work bowl of food processor with the flour, spreading it around evenly, then add the powdered almonds, sugar, minced lemon skin, and a pinch of salt. Switch on the motor for about 1 second to sift all these and blend them together. Stop the motor.

Now drop in, neatly, all around, the dollops of the fairly hard butter. Run the motor until the butter has been amalgamated to the consistency of niblet corn -- usually in a 1-second burst, but maybe after a second one, or a third. Stop the motor, and check after each burst.

When you have the niblet corn, add the liquid ingredients, the egg yolks and sprinkle with the rum. Start the motor again immediately and watch carefully, until the dough forms a single ball -- in about 20 to 25 seconds. Stop the motor instantly, very lightly flour the pastry board, and transfer the dough to it -- scraping out any bits lurking in corners or under the blades in the work bowl. Knead and shape the dough for only a few seconds. Do not overwork it.

(If you are using an electric beater-mixer with the dough hook in position, follow the same general procedure, with the motor running at its slowest speed. By hand, mix the dry ingredients first, with a wooden spatula, then make a hole in the center, put in the butter and work it lightly to the niblet stage with your fingers. Then work in the egg yolks and the rum to achieve approximately the same final results.)

Finally, on the pastry board, gather it all into a single, solid mass, then break it up into separate balls of just about 200 grams (7 ounces) each. Wrap each tightly in a cellophane bag and regrigerate overnight. Those to be used at a later date can be frozen if you like.

Mixing the filling: Preheat the oven to 400 degrees and adjust the main shelf so the tart will be baked exactly in the center of the oven. Take one of the balls of pastry dough out of the refrigerator just about 20 minutes (or out of the freezer, about one hour before starting to roll it out on the lightly floured pastry board. The dough must be neither too hard nor to soft. l

Roll out the pastry to a circle 12 inches in diameter. Lift it carefully, holding one hand underneath it, and lay it exactly in the center of an 8-inch tart pan. Tuck it down lightly, across the bottom, in the corners and down the sides. With the large fork, thoroughly prick the bottom. Roll back the overhanging edges and press them or cut them, into a ratchet edge. Now put the tart shell in the refrigerator.

Put into the mixing bowl the coconut, vanilla sugar, a pinch (or two, to your taste) of powdered cinnamon, the whole eggs (lightly beaten), the cream, and 2 tablespoons of the rum. Blend everything thoroughly.

As soon as the oven is hot, bring the tart shell out of the refrigerator, fill it lightly and evenly with the coconut-rum mixture, and slide it all into the center of the oven. Bake it until a shiny knife poked in the center comes out clean, indicating that the filling is set all the way through -- usually 20 to 25 minutes depending on the efficiency of the oven.

After baking, as the tart begins to cool, sprinkle evenly cross the top the remaining rum. Serve this lovely tart warm.

Working Notes: Keep a supply of easy-to-make vanilla sugar among your staples. You need 2 pounds of super-fine white sugar, two long, whole vanilla beans, and a tightly-lidded jar to hold them.

Put in the sugar. Cut each vanilla bean, crosswise, into three pieces -- six pieces in all. Cut each of these pieces in half, lenghtwise, exposing the central core and seeds, from which the maximum flavor oils emanate. Dig these pieces down into all parts of the sugar. Hold the jar, tightly closed, for a week or two.

You will find that all the sugar is strongly permeated with the vanilla flavor. Try it to sweeten your coffee or hot chocolate -- or sprinkle it over fruits or yogurt.

As the sugar is used up, add more to the jar. Depending on the amount of use, the vanilla pieces should continue giving off flavor for six to nine months. When the pieces are completely dry and brittle with no more vanilla scent, replace them.