Ham & Cheese Croissant Recipe

Prepare croissants

Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper. If croissants are straight from the refrigerator and slightly firm, warm them on the counter 10–15 minutes so they are easier to slice.

Split croissants

Using a sharp serrated knife, carefully slice each croissant horizontally about three-quarters of the way through so the two layers remain attached at the back. Open gently to create a pocket for fillings.

Butter and mustard

In a small bowl, mix the unsalted butter with Dijon mustard (and whole-grain mustard if using) until well combined. Spread about 1/2 tablespoon of the butter-mustard mixture on the cut interior of each croissant (reserve any extra for serving).

Assemble ham and cheese

Place two slices of ham folded or layered into each croissant, tucking them neatly into the pocket so they cover most of the interior. Top the ham with one slice of Swiss cheese per croissant. Sprinkle a little freshly cracked black pepper over the cheese (about 1/4 teaspoon per croissant).

Optional egg wash

If you want a glossy exterior, whisk the egg with 1 teaspoon water to make an egg wash. Lightly brush the exposed croissant surface (not the interior) with the egg wash using a pastry brush. This step is optional for store-bought croissants but gives extra sheen and color after warming.

Warm and melt

Place the assembled croissants on the prepared baking sheet and bake in the preheated oven for 8–12 minutes, until the cheese is melted and croissants are heated through and slightly crisp on the outside. If you used egg wash, bake toward the lower end of the time to avoid over-browning, checking after 8 minutes.

Finish and serve

Remove the croissants from the oven. Let them rest 1–2 minutes, then transfer to plates. If desired, brush any reserved butter-mustard on top or sprinkle with chopped parsley. Serve warm.

Make it heartier: add a thin slice of tomato or a few baby spinach leaves inside before warming. For a richer sandwich, spread a teaspoon of mayonnaise or softened cream cheese on the interior instead of or in addition to mustard.

Crispier finish: after melting the cheese, place croissants under a preheated broiler for 30–60 seconds to brown the top—watch carefully to avoid burning.