1 cup pure maple syrup
3 1/2 cups whipping cream
7 large egg yolks
1/8 teaspoon salt
2/3 cup sugar
1/4 cup water
1/2 teaspoon light corn syrup
1 tablespoon unsalted butter
3 ripe Bartlett pears, unpeeled, quartered, cored
1/4 cup pure maple syrup
1/4 cup crème fraîche or sour cream
1/8 teaspoon salt
Simmer maple syrup in heavy medium saucepan over medium-low heat until reduced to 3/4 cup, about 7 minutes. Stir in cream; return to simmer.
Whisk egg yolks in large bowl to blend. Gradually whisk in hot cream mixture. Whisk in salt. Strain custard into another large bowl. Cover and chill until cold, at least 2 hours and up to 1 day.
Preheat oven to 300°F. Stir sugar, 1/4 cup water, and light corn syrup in heavy medium saucepan over low heat until sugar dissolves. Increase heat and boil without stirring until syrup is deep amber color, occasionally brushing down sides of pan with wet pastry brush and swirling pan, about 6 minutes. Pour syrup into 9 1/4x5 1/4x3-inch nonstick metal loaf pan, tilting pan carefully to coat sides. Let stand 10 minutes.
Pour custard into pan with syrup. Place loaf pan in large roasting pan. Add enough hot water to roasting pan to come halfway up sides of loaf pan. Cover roasting pan with foil. Pierce foil all over with fork. Bake flan 1 hour 45 minutes. Increase oven temperature to 325°F. Uncover and bake until flan is set around edges but center moves slightly when pan is gently shaken, about 1 hour longer. Remove flan from water. Transfer to rack; cool to room temperature. Cover and refrigerate overnight.
Preheat oven to 375°F. Melt butter in heavy large ovenproof skillet over medium-high heat. Arrange pears, 1 cut side down, in skillet. Cook until brown, about 4 minutes. Turn onto second cut side and cook until brown, about 4 minutes longer. Stir in maple syrup; bring to boil. Place in oven and bake until pears are tender, about 25 minutes. Using slotted spoon, transfer pears to plate. Whisk crème fraîche and salt into sauce in skillet. Return pears to skillet and toss to coat.
Run sharp knife around edge of flan to loosen. Invert flan onto platter. Surround with pears and sauce.