Makes 8 servings
Butter a 13 x 9 inch baking dish. Cut 24 I-inch slices from baguette and arrange in one layer in baking dish. In a large bowl whisk together eggs, milk, nutmeg, vanilla and 3/4 cup brown sugar and pour evenly over bread. Chill mixture, covered, until all liquid is absorbed by bread, at least 8 hours, and up to 1 day. Preheat to 350 degrees.
In a shallow baking pan spread pecans evenly and toast in middle of oven until fragrant, about 8 minutes. Toss pecans in pan with 1 teaspoon butter and salt.
Increase temperature to 400 degrees.
Sprinkle pecans and blueberries evenly over bread mixture. Cut 112 stick butter into pieces and in a small saucepan heat with remaining 1/4 cup brown sugar, stirring until butter is melted. Drizzle butter mixture over bread and bake mixture 20 minutes, or until any liquid from blueberries is bubbling.
Make syrup: In a small saucepan cook blueberries maple syrup over moderate heat until berries have burst, about 3 minutes. Pour syrup through a sieve into a heatproof pitcher, pressing on solids, and stir in lemon juice. Syrup may be made 1 day ahead and chilled, covered. Reheat syrup before serving