Croque Monsieur Recipe

Prepare croissants

Preheat your waffle iron to medium-high heat. Split each croissant horizontally into two even layers (like a sandwich). If croissants are large, press slightly to flatten to about 1/2–3/4" thickness so they crisp evenly in the waffle iron.

Brush the cut surfaces lightly with melted butter (about 1/2 tbs per croissant half) to promote browning and crispness. Reserve remaining melted butter for later.

Place croissant halves, cut-side down, in the hot waffle iron (work in batches if needed). Close the iron and cook until the croissant is crisp and golden and has waffle indentations, about 2–3 minutes depending on your iron. Remove and keep warm on a wire rack. Repeat with remaining croissant halves.

Make the béchamel

In a small saucepan over medium heat, melt 2 tbs unsalted butter. Add 2 tbs all-purpose flour and whisk continuously to form a smooth roux; cook 1–1 1/2 minutes without browning to remove raw flour taste.

Gradually whisk in 1 cup whole milk in a steady stream to avoid lumps. Continue whisking until the sauce thickens and is smooth, 3–5 minutes. Reduce heat to low.

Stir in 1 tsp Dijon mustard, a pinch of freshly grated nutmeg, 1/2 tsp salt, and 1/4 tsp black pepper. Taste and adjust seasoning. Remove from heat — the béchamel should be pourable but coat the back of a spoon.

Assemble croque monsieur waffles

Preheat your oven to 375°F (190°C). On the waffle-bottom halves (or one crisped half acting as base), spread a thin layer of Dijon mustard (~1/4 tsp per sandwich). Top each with 2 slices of ham (or equivalent) and a generous sprinkle of grated Gruyère (about 1/4–1/3 cup per sandwich). Place the second croissant waffle half on top to form a sandwich.

Place assembled sandwiches on a baking sheet lined with parchment. Spoon or evenly pour a tablespoon or two of béchamel over the top of each sandwich, then sprinkle with the remaining Gruyère and the optional Emmental so the top is well covered (about 2–3 tbs additional cheese).

Brush the exposed croissant edges lightly with the reserved melted butter to encourage golden color.

Bake in the preheated oven until the cheese topping is melted, bubbling, and beginning to brown, about 8–10 minutes. For a deeper gratin finish, switch to broil for 1–2 minutes while watching closely to avoid burning.

Remove from oven and let rest 1–2 minutes. Brush the edges with 1 tbs melted butter for shine and extra flavor.

Garnish with chopped fresh parsley if using. Serve hot so the cheese is melty, with a simple green salad or mustard on the side.