Toast croissants: Preheat oven to 350 degrees F. Add the cubed croissants in a single layer to a large baking sheet (15x21-inches). Bake 350 degrees F for 7-10 minutes until golden and very toasted (keep an eye on them so they don’t burn!). Set aside to cool.
Custard: Add cream cheese and sugar to a large mixing bowl and beat with a hand mixer until smooth. Beat in the eggs until smooth, followed by the half and half, and finally the lemon juice, lemon zest, vanilla extract and salt.
Assemble: Transfer half of the croissants to a lightly greased 9x13 baking dish, then evenly layer with half of the berries. Pour half of the custard evenly over the dish. Add remaining croissants in a single layer followed by remaining custard. Press down with your hands so most of the croissants are submerged in the custard (it’s okay if the tops aren't). Scatter remaining berries over the dish. Cover with foil and refrigerate overnight.
Bake: When ready to bake, remove the casserole from the refrigerator and let it sit on the counter while you preheat the oven to 350 F degrees. Bake, covered with foil, for 30 minutes. Remove the foil and bake, uncovered, for an additional 15 minutes, or until a knife inserted in the center comes out clean.
Lemon Glaze: While the casserole is baking, make the Lemon Glaze. Add all of the Glaze ingredients to a medium mixing bowl and beat with a hand mixer until smooth. Taste and add additional sugar for sweeter or lemon juice for tangier. Drizzle the glaze all over the casserole.
Serve: Serve the breakfast casserole warm. Let individuals dust their servings with powdered sugar if they would like it sweeter.