01 -
Preheat the oven to 350°F (175°C). Arrange halved croissants, cut side up, on a parchment-lined baking sheet. Toast in the oven until golden, approximately 10-12 minutes. Allow croissants to cool before tearing into large bite-size pieces.
02 -
Evenly place torn croissants into the bottom of a 9x13-inch baking dish.
03 -
In a skillet over medium heat, cook chopped bacon until crisp. Remove bacon using a slotted spoon and place on a paper towel-lined plate. Reserve 1 tablespoon of the bacon grease in the skillet.
04 -
Return the skillet with reserved bacon grease to medium heat. Add diced shallot or red onion with a pinch of salt and pepper. Sauté for 3-5 minutes until translucent.
05 -
Sprinkle cooked bacon, sautéed onions, and shredded cheese evenly over the torn croissants in the baking dish. Lightly toss, if desired, to distribute evenly.
06 -
In a medium bowl, whisk together eggs, milk, heavy cream, salt, and black pepper until fully combined. Pour the mixture evenly over the casserole layers.
07 -
Cover the baking dish and refrigerate for a minimum of 4 hours, up to a maximum of 12 hours. Avoid exceeding 12 hours to prevent croissant disintegration.
08 -
Preheat the oven to 350°F (175°C). Remove the cover from the casserole and place the baking dish on a foil-lined baking sheet to catch possible spillovers. Bake for 45-50 minutes, until golden, puffy, and firm to the touch.
09 -
Allow the casserole to rest for 10-15 minutes before serving.