Croque Monsieur Breakfast Casserole

Ingredients

• 1 large loaf country-style bread, cut into 1“ cubes
• 6 large eggs
• 1 c. half-and-half
• 1/4 c. Dijon mustard
• Kosher salt
• Freshly ground black pepper
• 4 tbsp. unsalted butter, plus more for pan
• 6 oz. shredded Gruyére (about 2 1/2 c.), divided
• 4 oz. ham, torn into 1“ pieces, divided
• 1/4 c. (30 g.) all-purpose flour
• 2 1/2 c. whole milk
• Pinch of ground nutmeg

Instructions

1. Preheat oven to 300°. On a baking sheet, spread bread in an even layer and bake until dried out and crispy, 10 to 15 minutes. Transfer to a large bowl.
2. In a large glass measuring cup, whisk eggs, half-and-half, and mustard; season with salt and pepper. Pour over toasted bread and toss to coat. Let soak 10 minutes.
3. Increase oven temperature to 350°. Grease a 13“-by-9“ baking dish with butter. Add about half of bread to prepared dish. Top with 1 cup Gruyére and half of ham. Top with remaining bread and pour remaining liquid over. Top with 1/2 cup Gruyére and remaining ham.
4. Bake casserole until bread is crispy and golden and cheese is melted, 30 to 40 minutes.
5. Meanwhile, in a medium pot over medium heat, melt butter. Add flour and whisk into butter. Cook, stirring occasionally, until golden and smells nutty, about 2 minutes. While whisking, slowly pour in milk and continue to whisk until smooth. Bring to a simmer and cook, stirring occasionally, until sauce is thickened enough to just coat a spoon, but not as thick as gravy, about 1 minute. Stir in nutmeg; season with salt and pepper.
6. Preheat broiler. Pour sauce over casserole and top with remaining 1 cup Gruyére.
7. Broil, watching closely, until cheese is melted and golden in spots, 2 to 5 minutes.