Croque Monsieur Recipe

Preheat oven to 230°C (450°F). Line a baking sheet with parchment or lightly oil it.

Wash and scrub the russet potatoes. Cut into 1/3–1/2 inch (8–12 mm) thick sticks. Pat dry thoroughly with paper towels to remove surface moisture.

Toss the potato sticks with neutral oil, 1/2 tsp salt, 1/8 tsp pepper and optional seasoning until evenly coated. Spread in a single layer on the prepared baking sheet without overcrowding.

Bake for 18–25 minutes, turning once halfway, until golden and crisp at the edges. If needed, broil 1–2 minutes to finish crisping—watch closely to avoid burning.

Remove from oven and taste for seasoning; adjust with more salt if desired. Keep warm while preparing sandwiches.

In a medium saucepan over medium heat, melt 3 tbs butter until foaming.

Add 3 tbs flour and whisk constantly to form a blond roux, cooking 1–2 minutes but do not brown.

Gradually whisk in 2 cups cold whole milk in a steady stream to avoid lumps. Continue whisking until the mixture thickens and comes to a gentle simmer, about 4–6 minutes.

Reduce heat to low. Stir in 1 cup grated Gruyère, 1 tbs Parmesan, and 1 tsp Dijon until melted and smooth.

Season the sauce with 3/4 tsp salt, 1/4 tsp pepper and 1/8 tsp nutmeg. Keep warm on the lowest heat, stirring occasionally. If sauce becomes too thick, whisk in a tablespoon of milk to loosen.

Preheat oven broiler or set oven to 200°C (400°F) if you prefer finishing in the oven. If using a skillet, heat it to medium-low.

Lightly butter one side of each bread slice (4 slices will be bottoms, 4 will be tops). The buttered side will be the exterior for grilling.

On the unbuttered side of 4 bread slices, place about 1/4 cup grated Gruyère (reserve remaining cheese for topping). Top with 2 slices ham per sandwich (or about 60 g), then another 1/4 cup grated Gruyère. Place remaining 4 bread slices on top, buttered side facing outward.

Heat a large skillet over medium heat and place sandwiches, buttered side down. Cook 2–3 minutes per side until golden brown and cheese begins to melt, pressing gently with a spatula. Alternatively, transfer assembled sandwiches to a baking sheet for oven finishing.

If finishing under the broiler or in the oven: place sandwiches on a baking sheet. Spoon a generous 2–3 tbs Mornay sauce onto each sandwich top, then sprinkle with the reserved 1/2 cup Gruyère (divide evenly). Broil 2–4 minutes until the sauce bubbles and the cheese topping is golden brown — watch carefully to prevent burning.

If using skillet only: after both sides are golden and internal cheese is melting, remove sandwiches to an ovenproof pan, spoon Mornay sauce over the tops, sprinkle with reserved Gruyère, and put under a preheated broiler 1–3 minutes until bubbly and browned.

Remove sandwiches from oven, let rest 1 minute, then sprinkle with chopped parsley if using. Slice each sandwich in half on the diagonal.