- Preheat oven to 400 degrees F. Toast challah bread for 10 minutes until it’s golden brown. Let cool and then tear into chunks.
- In a medium skillet add olive oil over medium heat. Add sausage and cook, breaking it up as it cooks, until well-browned. Add shallots near the end a cook for another few minutes to soften shallots.
- Transfer sausage mixture with any drippings in skillet to a large bowl with challah chunks. Toss together.
- In a separate bowl, whisk together eggs, milk, and cream. Pour mixture into larger bowl with challah and sausage. Stir to combine and let sit for a few minutes.
- Transfer half of the casserole mixture to a large 9×13 baking dish. Top with half of the grated cheese. Then top with the rest of the casserole mixture followed by the last of the cheese. Season with salt and pepper.
- Let casserole sit in the fridge overnight (at least a few hours).
- When ready, bake casserole at 350 degrees F. for 45 minutes until it’s puffed and browned around the edges. Let rest for 10 minutes before serving. Serve garnished with fresh scallions.
Adapted from a NY Times recipe.