With the popular Shavuot custom of including dairy products in holiday menus, this is the perfect time to serve the choicest ones. When I think of ingredients that made me exclaim "wow!" - three of the finest of creams stand out in my memory: French crÃ¨me fraÃ®che, Italian mascarpone and Turkish kaymak. No wonder "crÃ¨me de la crÃ¨me" in French means the best of the best or the cream of the crop. Cream is the butterfat that naturally rises to the top in nonhomogenized milk. The two main types are sweet and sour cream. The term sweet cream does not indicate that sugar has been added. Rather, it means that the cream has the naturally sweet flavor of the milk, in contrast to a cultured cream like sour cream, which contains some acidity. "What's the difference between heavy cream and light cream?" students in my cooking classes often ask. "Can I boil light cream to thicken a sauce?" is another frequent question. The answers to both these questions lie in the cream's fat content. The high butterfat content of whipping cream, which exceeds 30 percent, enables it to be whipped or boiled down without separating. Light cream or coffee cream has about 10% to 15% fat and cannot be whipped or boiled. If you add it to a sauce, you should heat the sauce gently without letting it bubble. (If you're making a flour-based sauce, however, you can bring the sauce to a boil even after you add coffee cream.) If you're following a British recipe, single cream is equivalent to light cream, and double cream is like heavy cream. Sour cream is made by adding a bacterial culture to cream and leaving it in a warm place until some of the lactose, or milk sugar, is converted to lactic acid. Sour cream cannot be boiled, as it curdles from excessive heat. French crÃ¨me fraÃ®che is also a cultured cream with a nutty flavor made by a somewhat similar process to sour cream. Unlike sour cream, it can be whipped and can be boiled in sauces to thicken them. When I left France in the early 1980s after years of cooking there, whenever I wanted crÃ¨me fraÃ®che, I had to make my own by heating heavy cream and adding yogurt. Today crÃ¨me fraÃ®che can be found at fine supermarkets. If you travel to the British Isles, look for English clotted cream, also called Devonshire or Devon cream, which is made by heating rich milk and skimming the cream from the surface. This sweet cream is so rich that it's almost as thick as soft butter. The favorite way to use it is to spread it on scones at teatime and top them with jam. When I was researching my book Feast from the Mideast, my husband and I visited Istanbul and there we tasted the ultra-rich Turkish clotted cream known as kaymak (and called eshta or ashta in other parts of the Mideast). It was incredible - so rich that it's sometimes rolled up in sheets. At the Istanbul Ritz Carlton breakfast buffet, every morning we could get fresh kaymak for spreading on sweet rolls - a sensational way to start the day. Later, on the Asian side of Istanbul, we found manda kaymak, made from the milk of water buffaloes, which is richer than cow's milk. The Turks use it to top sweet, fruity desserts, such as poached quinces. Don't miss it if you vacation in Turkey. My Afghani friend, Ghulam Nabi, told me that kaymak is made in his country from the milk of cows, goats and sheep, and is popular in sweetened green tea flavored with cardamom and rose petals. Helen Saberi, author of Afghan Food & Cookery, wrote that this is a special tea for formal occasions, such as engagements or weddings. If you come across a recipe that calls for kaymak, you can substitute crÃ¨me fraÃ®che or even Italian mascarpone. Steven Jenkins, author of The Cheese Primer, calls mascarpone "more a dairy product than a cheese," as no starter or rennet is used. Its texture reminds me of crÃ¨me fraÃ®che and it's made in a similar way except that it is not aged, but is sold right away while still fresh and sweet. In southern Italy, by the way, mascarpone is sometimes made from water buffalo milk. When kaymak is called for as an accompaniment, some cooks use whipped cream instead. Benny Saida, author of Food from the Balkans (in Hebrew), suggests making kaymak for desserts by making sweetened whipped cream and folding in sour cream, the richest available - the kind with 27% butterfat ("shamenet shel pa'am"). As with yogurt and cheeses, sour cream and sweet cream formulas from different companies vary, giving subtle differences in taste. In France, for example, the region of Normandy is the most famous for the quality of its crÃ¨me fraÃ®che. We all know that cream, whether cultured or whipped, is wonderful with fresh and poached fruit and with almost all desserts. On the savory side of the menu, heavy cream and crÃ¨me fraÃ®che greatly enhance fish bisques, vegetable soups and sauces for fish and for pasta. Sour cream is good in soups and sauces too, but is best beaten into the sauce off the heat, or heated only slightly. Thai chef Somchit Singchalee, who studied French cooking with me in Paris, found a novel use for crÃ¨me fraÃ®che. She made a very spicy Thai red curry with coconut milk and finished it with a ladleful of the luscious crÃ¨me fraÃ®che. Chef Singchalee explained that the crÃ¨me fraÃ®che helps to smooth out the spiciness while adding its own slightly tangy flavor. It was the best Thai curry I have ever tasted. BAKED SALMON WITH MUSHROOM SOUR CREAM SAUCE This entree, which makes a delightful centerpiece for a Shavuot meal, illustrates how to use sweet cream and sour cream to enrich a sauce. The delicate sauce is wonderful not only with baked salmon, but also with halibut, cod or sole, or with any food you like with a creamy sauce. The ideal side dish, for my taste, is fresh noodles or steamed potatoes. You can saute the mushrooms and make the sauce with the milk and whipping cream in advance. A short time before serving, heat the sauce and add the mushrooms and sour cream. 4 small salmon steaks or 4 portions salmon fillet, about 2.5 cm. thick 1 Tbsp. strained fresh lemon juice 1â„2 Tbsp. vegetable oil Salt and freshly ground pepper pinch of hot paprika or cayenne pepper 175 to 225 gr. small mushrooms 2 Tbsp. butter 1â„4 cup chopped green onion (mostly white part) 2 tsp. all-purpose flour 1â„4 cup milk 1â„2 cup whipping cream 1 tsp. sweet paprika 1â„2 cup sour cream, room temperature 2 Tbsp. chopped parsley Preheat oven to 230Âº. Set salmon in a heavy roasting pan. Sprinkle fish with lemon juice and 1â„2 tablespoon oil and rub them over fish. Sprinkle fish with salt, pepper and, if you like, a little hot paprika. Roast salmon uncovered for 12 to 15 minutes or until flesh can just flake and has changed color in its thickest part. Quarter mushrooms. Melt 1 tablespoon butter in a large skillet. Add mushrooms, salt and pepper and saute over medium-high heat about 5 minutes or until tender and lightly browned. Remove from skillet and reserve. Melt remaining butter in skillet. Add green onion and saute over medium heat for 2 minutes. Sprinkle with flour and cook over low heat, stirring, for 1 minute. Gradually stir in milk and whipping cream. Add sweet paprika and a little salt and pepper. Simmer over medium heat, stirring, until sauce is thick enough to coat a spoon. A short time before serving, reheat sauce if necessary. Add mushrooms and sour cream and heat gently, stirring, without boiling. Add hot paprika. Taste and adjust seasoning. Remove from heat. Add parsley. Serve salmon hot, accompanied by the sauce. Makes 4 servings. Faye Levy is the author of the three-volume Fresh from France cookbook series and of 1,000 Jewish Recipes.