How to Make It
Preheat the oven to 350°. Line the bottom and sides of a 12-by-16-inch jelly-roll pan with aluminum foil and coat with cooking spray. Arrange the brioche slices in the prepared pan, fitting them in a snug single layer.
In a medium heavy saucepan, combine the milk with 1/4 cup plus 2 tablespoons of the sugar and bring to a simmer. In a medium bowl, whisk the eggs with the remaining 1/4 cup plus 2 tablespoons sugar. Whisk 1 cup of the hot milk into the eggs, then whisk in the remaining hot milk until thoroughly blended. Add the lemon zest and slowly whisk in the lemon juice. Pour the custard mixture evenly over the brioche and soak for 10 minutes.
Bake the brioche on the middle rack of the oven for 30 minutes, turning the pan halfway through. Transfer the pan to a cooling rack and let the bread pudding cool to room temperature, about 1 hour. Refrigerate until chilled, 1 hour.
Line a 10-by-5-inch loaf pan with plastic wrap, allowing 3 inches of overhang. Lightly coat the inside of the plastic wrap with cooking spray.
Trim 1/2 inch off the edges of the bread pudding. Cut the bread pudding into three 5-by-11-inch strips. Gently press 1 strip of the bread pudding into the loaf pan. Spread 3/4 cup of the Lemon Curd evenly over the bread pudding. Repeat to form a second layer of pudding and curd. Press the last piece of bread pudding on top. Cover with overhanging plastic wrap and refrigerate overnight.
In a medium bowl, beat the heavy cream until stiff. Fold in the remaining 1/2 cup of Lemon Curd. Uncover the bread pudding and turn it out onto a serving plate; remove the plastic wrap. Using a hot knife, slice the bread pudding 3/4 inch thick, top with a dollop of the lemon whipped cream and serve.