Preheat oven to 375 degrees. Place the sliced potatoes in water to cover until needed. Heat oil in a medium saute pan until very hot. Add garlic, shallots, and onions and saute 2 to 3 minutes, until you can smell the aroma. Add sherry and boil over high heat to reduce until about 1/4 cup of liquid remains. Remove from heat and allow to cool. Lightly oil a 9 by 5-inch baking dish. Cover the bottom with about a third of the potatoes. Sprinkle with about a third of the onion mixture, then sprinkle with about a third of the cheese and the basil. Drizzle about 1/3 cup cream over the potato mixture and season lightly with salt and pepper. Top with another layer of potatoes and repeat the process. Top with one final layer of potatoes and repeat the process. Bake for about 40 minutes, or until the potatoes are fork-tender and the cheese is golden brown. Serves four. Per serving: 1812 Calories (kcal); 114g Total Fat; (59% calories from fat); 37g Protein; 135g Carbohydrate; 358mg Cholesterol; 890mg Sodium Food Exchanges: 7 1/2 Grain(Starch); 2 1/2 Lean Meat; 3 Vegetable; 0 Fruit; 21 Fat; 0 Other Carbohydrates Converted by MM_Buster v2.0n.