1. Preheat the oven to 350 degrees F.
2. Put the pear slices in a large saute pan with 2/3 cup sugar, the salt, pear liqueur, and lemon juice. Cook the mixture, stirring occasionally, over medium heat for about 10 minutes, until the pears are soft. Set aside to cool.
3. Place the butter, the remaining 1 tablespoon of sugar, and the cinnamon in the bowl of an electric mixer. Using the paddle attachment on medium speed, cream the mixture until it is smooth.
4. Butter each piece of brioche with the cinnamon butter. With the long side of the bread closest to you, cut each slice into 3 pieces. Line the sides of the ramekins with the brioche pieces, buttered-side against the ramekin.
5. Compactly fill the inside of each ramekin with about 1/4 cup of the pear mixture. Trim off any brioche that sticks up above the ramekin.
6. Bake the charlottes for 15 to 20 minutes, until the brioche is toasted.
7. Spoon some of the vanilla custard sauce on 4 plates, and unmold the charlottes on top.
8. Top each with a dollop of creme fraiche.
Makes 8 servings, Difficulty: Intermediate