Follow these simple step-by-step instructions to bake the perfect Ham Swiss Croissant Bake. It’s easier than you think!

1. Preheat the Oven and Prepare Baking Dish: Preheat your oven to 350°F (175°C). Grease a 9×13 inch baking dish with butter or cooking spray. This will prevent sticking and make cleanup easier.
2. Prepare the Croissants: Slice each croissant in half lengthwise. If your croissants are very fresh and soft, you might want to let them sit out for a few hours or lightly toast them in the oven (at a low temperature like 200°F for 5-7 minutes) to dry them out slightly. This helps them absorb the egg mixture without becoming soggy. Arrange the croissant halves in the prepared baking dish, cut-side up, in a single layer. You may need to slightly overlap them to fit them all in.
3. Layer Ham and Swiss Cheese: Distribute the diced ham evenly over the croissant halves in the baking dish. Then, sprinkle the shredded Swiss cheese generously over the ham. Make sure to get cheese into all the nooks and crannies between the croissants for maximum cheesy goodness.
4. Whisk the Egg Mixture: In a large bowl, whisk together the eggs, heavy cream, milk, Parmesan cheese, Dijon mustard, chopped chives, dried thyme, salt, pepper, and nutmeg (if using). Whisk until everything is well combined and the mixture is smooth and slightly frothy. The Dijon mustard adds a subtle tang that complements the richness of the cream and cheese.
5. Pour Egg Mixture Over Croissants: Slowly and evenly pour the egg mixture over the croissants, ham, and Swiss cheese in the baking dish. Make sure the mixture seeps down into all the layers and saturates the croissants. You might need to gently press down on the croissants with a spatula to ensure they are all soaking up the liquid.
6. Optional: Brush with Melted Butter: For an extra golden and buttery crust, lightly brush the tops of the croissants with the melted butter. This step is optional but highly recommended for added flavor and visual appeal.
7. Bake: Place the baking dish in the preheated oven and bake for 30-40 minutes, or until the croissants are golden brown and puffed, and the egg mixture is set. To check if it’s done, insert a knife into the center; it should come out clean. The top should be nicely browned and the edges slightly crispy.
8. Let it Rest and Garnish: Once baked, remove the Ham Swiss Croissant Bake from the oven and let it rest for 5-10 minutes before serving. This allows the egg mixture to set further and makes it easier to slice and serve. Garnish with extra fresh chives or parsley, if desired, for a pop of color and freshness. Optional garnishes like everything bagel seasoning or red pepper flakes can be sprinkled on top just before serving for added flavor and visual appeal.
9. Serve Warm: Slice the Ham Swiss Croissant Bake into squares or portions and serve warm. It’s delicious on its own or with your favorite brunch sides.