How to Make It
Stir together brown sugar, melted butter, and 1/4 cup of the maple syrup. Spread mixture into a 13- x 9-inch baking dish lightly coated with cooking spray. Sprinkle with 3⁄4 cup of the pecans. Arrange baguette slices evenly on top.
Whisk together next 5 ingredients and 1 teaspoon of the vanilla. Pour over baguette slices. Cover; chill 8 hours.
Preheat oven to 350°F. Remove baking dish from refrigerator; let stand at room temperature 10 minutes. Bake, uncovered, until golden brown and set, about 35 minutes.
During final 10 minutes of baking, combine bourbon and remaining 3/4 cup maple syrup and 1/4 teaspoon vanilla in a saucepan. Cook over low, stirring, until warm, 2 minutes. Remove from heat; cover pan.
Sprinkle casserole with powdered sugar and remaining 1/4 cup pecans. Serve with Bourbon-Maple Syrup.