Recipe from The Boston Globe
¼ cup (½ stick) unsalted butter, melted
6 pints fresh blueberries, picked over
1 cup sugar
grated rind and juice of 2 lemons
3 tablespoons water
12 slices challah, brioche, or other tender, eggy white bread (half of the bread sliced ¾-of-an-inch thick, half of the bread sliced ½-inch-thick)
extra sugar (for sprinkling)
Set the oven at 375˚F. Using some of the butter, butter a deep 3-quart baking dish.
In a saucepan over medium heat, combine the blueberries, sugar, lemon rind and juice, and water. Cook, stirring often, for 5 minutes or until some berries collapse. The mixture will be slightly juicy-you can add a little cornstarch if desired to thicken it but we didn’t find it necessary.
With a brush, dab butter on one side of each slice of bread. Layer half of the berries and then the ¾-inch thick slices of bread, beginning and ending with berries, in the dish. Press down on the bread with a spoon to submerge it. For the top layer of berries we used a slotted spoon to remove the berries and leave some of the excess liquid in the pan (you won’t need to do this if you add cornstarch.)
On the top layer, overlap the remaining ½-inch-thick slices of bread, buttered sides up, to form a pattern. Sprinkle the top generously with sugar.
Bake the slump for 25 minutes or until the top is golden (watch the bread carefully so it does not burn). Tent with foil if the bread browns too quickly. Cool for 10 minutes. Serve with vanilla ice cream.