Step 1

If planning to bake immediately, preheat the oven to 425°F. Grease a 9x13-inch baking dish with nonstick cooking spray or butter.

Step 2

Slice the bread into 1/2-inch-thick slices, then cut each slice in half. Arrange half of the bread in overlapping layers in the baking dish. Sprinkle the bread with about half of the lemon zest.

Step 3

Whisk the eggs in a large bowl until well mixed, then whisk in the brown sugar. Whisk in the milk, vanilla, salt, nutmeg, and remaining lemon zest. Pour half of the custard over the bread. Layer the rest of the bread on top, and pour the rest of the custard over to coat. (At this point the casserole can be covered and refrigerated for up to 24 hours.)

Step 4

When ready to bake, take the casserole out of the refrigerator and let sit at room temperature for at least 10 minutes before baking. Heat the oven to 425°F. Bake the casserole for 30 minutes, or until slightly golden on top, and puffy.

Step 5

Whisk the lemon juice with the confectioners' sugar and drizzle the glaze over the hot casserole. Put a few teaspoons of confectioners' sugar in a small sieve or strainer, and dust the top of the casserole by tapping the strainer lightly over it.

Step 6

Let the casserole cool for at least 15 minutes before serving. Serve in large slices, with raspberries on the side.

Step 7

Toss the raspberries, gently, with the cava. Chop the mint leaves very fine and toss with the berries as well. Refrigerate until serving.