Ham and Cheese Croissant Casserole Is a Clever Take on Croque Monsieurs

In this clever way to re-purpose leftover store-bought mini croissants, savory ham slices and nutty, creamy Gruyère are tucked between layers of buttery, flaky croissants. The mini croque monsieurs (minus the béchamel) are then soaked  in a rich egg mixture and baked into a casserole. The final result is a velvety custard peppered with hearty croissant sandwiches in every bite.

What is deli-sliced ham?

Deli-sliced ham refers to pre-cooked or cured ham — typically black forest, honey, or smoked ham — that’s sold at deli counters in grocery stores or delicatessens. Unlike pre-packaged cold cuts, you can ask the counter staff for slices of a specific size, depending on how you plan to use them.

What if I don’t have day-old croissants?

This recipe calls for day-old croissants. Their drier texture allows them to soak up the custard without becoming soggy, a method similar to a bread pudding recipe. It’s a perfect way to use leftover croissants, but if you don’t have any, fresh croissants will work too. Simply dry them out by toasting them in the oven. Place your croissant halves on a baking sheet and bake at 250°F for 15 to 20 minutes. The low temperature ensures they dry out without burning. 

Notes from the Food & Wine Test Kitchen

To save time, you can tear the croissants into large pieces and arrange them in the baking dish with the other ingredients, instead of making individual sandwiches.

Make ahead

Assemble the casserole through Step 3 up to one day in advance. Cover and store it in the refrigerator overnight. Let the casserole sit at room temperature for at least 30 minutes while the oven preheats. Store leftovers in an airtight container for up to three days.