For the bread puddings

1. To prepare puddings, whisk together the milk, sugar, lemon zest, and eggs in a large bowl. Add bread and toss gently with a rubber spatula until all the bread pieces are evenly coated. Cover and let soak in the refrigerator for 1 to 4 hours.
2. Heat oven to 350 degrees F. Spray 8 (6-ounce) ramekins with cooking spray.
3. Divide half of bread mixture evenly among the ramekins. Sprinkle evenly with half of the blueberries. Divide remaining bread mixture among ramekins and top with remaining blueberries.
4. Cover each ramekin with foil. Place ramekins in a 13×9-inch baking pan; add hot water to pan to a depth of 1 inch. Bake, covered, for 15 minutes. Remove the foil and bake an additional 20-30 minutes or until a knife inserted in center comes out clean.

For the lemon curd

1. While the puddings bake, prepare the curd – whisk together the sugar and egg in a small saucepan. Cook the mixture over medium heat for 2 minutes or until sugar dissolves and mixture is light in color, whisking constantly. Stir in lemon juice and butter; cook 2 minutes more or until mixture thickens enough to coat the back of a spoon, whisking constantly.
2. Place saucepan in a bowl filled with ice water, being careful to not let any water fall into the curd. Stir the lemon curd occasionally until it cools to room temperature. Serve lemon curd over warm bread puddings.