Preheat the oven to 350°F. Spray a 9x13-inch baking dish with nonstick spray.
Spread the croissants evenly on a baking sheet. Drizzle the butter over the top and lightly toss together with your hands. Bake 6 to 8 minutes, stirring once or twice for an even toast without burning. Let cool.
In a large mixing bowl, beat the cream cheese and sugar with a hand mixer on medium speed until smooth and fluffy. Mix in the eggs. Slowly mix in the heavy cream. Mix in the milk, almond extract, salt, orange juice, and orange zest until well combined.
Using a wooden spoon, fold the croissants into the custard mixture until well coated. Let sit 5 minutes and gently stir again.
Add 1/2 of the croissants to the baking dish. Top with 1/2 pint blueberries and 1/4 pint raspberries. Spread the remaining croissants and any extra custard mixture over the fruit. Top with the remaining 1/2 pint blueberries and 1/4 pint raspberries. Cover with foil and chill at least 8 hours or up to 12 hours.
When ready to bake, remove the baking dish from the refrigerator and let sit at room temperature while the oven preheats. Preheat the oven to 350°F. Bake covered 30 minutes. Remove the foil and continue baking 15 to 20minutes, or until the top is golden brown and the custard is set.
Glaze
In a small bowl, whisk the powdered sugar, almond extract, orange juice, and 1 tablespoon of heavy cream until smooth and can be easily drizzled. If too thick, add additional heavy cream. If too thin, add more powdered sugar.
Drizzle the glaze over the warm casserole and sprinkle with sliced almonds, if desired.
Notes
Cream cheese: It’s important that the cream cheese be very soft. I even softened it in the microwave.Storage: Leftovers will last in an airtight container in the refrigerator up to 3 days.