Croque Monsieur Bake

All the glory of a Croque Monsieur—ham, béchamel, mustard and bubbling cheese—layered like a lasagna into a sliceable, golden-topped bake.

Ingredients

• 12 slices sandwich bread (white or brioche-style preferred)
• 12 oz (340g) sliced ham
• 10 oz (280g) Gruyère cheese, grated (or Swiss)
• 1/2 cup (50g) Parmesan, finely grated (optional but excellent)
• 4 tbsp (56g) unsalted butter
• 1/4 cup (32g) all-purpose flour
• 3 cups (720ml) milk (warm is best)
• 1 tsp Dijon mustard (plus extra for layering)
• 1/2 tsp salt, plus more to taste
• 1/4 tsp black pepper
• Pinch nutmeg (optional but classic)
• 2 tbsp melted butter (or olive oil)
• 1 tbsp Dijon mustard (optional, for extra “Croque” punch)

Method

• 1

  Step 1: Prep the oven + dish

  Heat oven to **400°F / 200°C** (180°C fan). Lightly butter a **9x13 in (23x33 cm)** baking dish.

• 2

  Step 2: Make the béchamel

  In a saucepan over **medium heat**, melt butter. Add flour and cook, whisking constantly, until it smells slightly nutty and turns pale blond, **1–2 minutes** (don’t let it brown).

• 3

  Step 3: Toast the bread lightly (structure trick)

  Lay bread slices on a baking tray. Brush lightly with melted butter (or a thin slick of oil). Toast in the oven **4–6 minutes**, flipping once, until just lightly dried and barely golden.

• 4

  Step 4: Layer 1

  Spread a thin smear of Dijon on **6 slices** of the toasted bread. Arrange them in the dish (overlap a little if needed to cover the base). Spoon over **about 1/3 of the béchamel**, spreading to the edges. Add **half the ham**, then sprinkle **about 1/3 of the Gruyère**.

• 5

  Step 5: Layer 2

  Add another **6 slices** bread (Dijon-smear optional but recommended). Spoon over **another 1/3 béchamel**, then the remaining ham, then **another 1/3 Gruyère**.

• 6

  Step 6: Top layer + finish

  Add a final layer of bread (you can use extra slices if your dish needs it—trim to fit). Spread the remaining béchamel all over the top, right to the corners.

• 7

  Step 7: Bake until bubbling and bronzed

  Bake **25–30 minutes** until the top is deeply golden, the sauce is bubbling at the edges, and the center is hot.

• 8

  Step 8: Rest, slice, serve

  Rest **10 minutes** (important for neat slices). Cut into squares and serve hot.

Tips

• **Cheese**: Gruyère is classic. Swiss works well. A little Parmesan on top adds the signature salty crust.
• **Bread**: Soft sandwich bread is ideal (Croque vibe). Brioche makes it richer. Avoid very dense sourdough—it can bake up too chewy in layers.
• **Make-ahead**: Assemble up to **12 hours ahead**, cover and refrigerate. Bake from cold adding **5–10 minutes** to cook time (cover loosely with foil if the top browns too fast).
• **Storage**: Refrigerate leftovers **up to 3 days**. Reheat in a **350°F / 175°C** oven until hot (microwave works, but oven keeps it crispier on top).
• **Serve with**: A sharp green salad with a simple vinaigrette (pantry: olive oil + vinegar + salt/pepper) cuts the richness beautifully.

Nutrition (per serving, estimate)