3 cups Maine wild blueberries, fresh or frozen, thawed, divided
½ cup maple syrup
1 Tbsp lemon juice (optional)
Ground cinnamon (optional)
For syrup, combine in a small saucepan over moderate heat one-half cup maple syrup and 1 cup blueberries; cook for about 3 minutes or until berries have burst. Strain syrup mixture to remove solids and add lemon juice, if desired. Syrup may be made ahead of time and reheated. Extra syrup keeps well refrigerated or frozen.
Cut French bread into 1" pieces. Butter or spray a 9" x 13" baking dish; lay the bread in the pan to cover bottom generously. Whisk together milk, 3/4 cup brown sugar, eggs, nutmeg, and vanilla and pour over the top of the bread, cover and let stand 1 hour or overnight in fridge.
Preheat oven to 350°. Spread pecans in a shallow baking dish and toast about 8 min until fragrant. Toss with 1 Tbsp butter and salt and set aside temporarily. Nuts may be prepared in advance. If desired, ground cinnamon may be added to the butter and salt.
Increase oven temperature to 400°. Sprinkle top of soaked bread with the toasted pecans and the 2 cups blueberries. Heat the 1/2 stick butter with the 1/4 cup brown sugar in a small sauce pan (ground cinnamon may be added to this topping, if desired); when liquid, combine and drizzle over bread. Bake for 1 hour or until puffed up and browned, and liquid from blueberries is bubbling. Casserole may need longer cooking if taken directly from the refrigerator than if at room temp.
Serve hot with warm or room-temp blueberry-maple syrup, and enjoy.