Croque Madame on Buttery Sourdough with Runny Egg

Why You’ll Love This Recipe

• Classic French comfort food: crisp, buttery sourdough with a creamy, silky béchamel.
• Balanced flavors: tangy Dijon, nutty Gruyère, savory ham, and a rich runny yolk.
• Fast but elevated: ready in about 30 minutes with simple techniques.
• Brunch showstopper or cozy dinner with a green salad.

Grocery List

• Produce: Fresh chives, whole nutmeg (optional)
• Dairy: Unsalted butter, whole milk, Gruyère cheese, eggs
• Pantry: Sourdough bread, Dijon mustard, all-purpose flour, kosher salt, black or white pepper, thinly sliced cooked ham (deli)

Full Ingredients

Béchamel Sauce

• 2 tbsp (28 g) unsalted butter
• 2 tbsp (16 g) all-purpose flour
• 1 cup (240 ml) whole milk, warmed
• 1/4 tsp kosher salt
• 1/8 tsp white pepper (or black pepper)
• Pinch (about 1/8 tsp) freshly grated nutmeg

Sandwiches

• 4 slices sourdough bread, 1/2-inch thick (about 240 g total)
• 2 tbsp (28 g) unsalted butter, softened (for the bread)
• 4 tsp (20 g) Dijon mustard
• 4 oz (115 g) thinly sliced cooked ham
• 3 oz (85 g) Gruyère cheese, grated (about 3/4 cup loosely packed)

Eggs and Finish

• 1 tbsp (14 g) unsalted butter (for frying eggs)
• 2 large eggs
• 1 tbsp finely chopped fresh chives
• Freshly ground black pepper, to taste

Step-by-Step Instructions

Step 1: Preheat and Prep

Set your oven rack 6 inches from the broiler and preheat the broiler to High. Line a rimmed sheet pan with foil or parchment for easy cleanup. Warm the milk in a small saucepan or in the microwave until steaming but not boiling. Grate the Gruyère and finely chop the chives.

Step 2: Make a Silky Béchamel

In a small saucepan over medium heat, melt 2 tbsp butter. Whisk in the flour and cook, whisking constantly, for 1 minute to remove the raw flour taste. Slowly drizzle in the warm milk while whisking to keep the sauce lump-free. Bring to a gentle simmer and cook 3–4 minutes, whisking, until thick enough to coat the back of a spoon. Season with kosher salt, white (or black) pepper, and a pinch of nutmeg. Reduce heat to low to keep warm, whisking occasionally.

Step 3: Toast the Sourdough

Spread softened butter on one side of each sourdough slice. Warm a large skillet over medium heat. Place the slices buttered-side down and toast until deeply golden, 2–3 minutes. Flip and toast the second side lightly, 1–2 minutes. Transfer to the sheet pan. Arrange slices so that the more deeply toasted sides will be the outsides of the sandwiches.

Step 4: Build the Sandwiches

Spread 2 tsp Dijon on the inner faces of two bread slices. Divide the ham between them and top with half of the grated Gruyère. Close with the remaining bread slices to form two sandwiches. Press gently to set the layers.

Step 5: Smother and Broil

Spoon the béchamel over the top of each sandwich, letting it drip slightly down the sides. Sprinkle with the remaining Gruyère and a pinch of black pepper. Slide under the broiler and cook 2–4 minutes, watching closely, until the sauce is bubbling and the cheese is spotty-browned. Rotate the pan once for even color if needed.

Step 6: Fry the Eggs and Finish

While the sandwiches broil, heat 1 tbsp butter in a nonstick skillet over medium heat. Crack in the eggs and cook until the whites are set and edges lightly crisp but the yolks remain runny, 2–3 minutes. Season with a pinch of salt and pepper. Top each sandwich with a fried egg and scatter with chives. Serve immediately while hot and crisp.

Pro Tips

• Warm milk makes a lump-free béchamel that thickens faster.
• Grate your own Gruyère for the best melt and flavor; pre-shredded often contains anti-caking agents.
• If the béchamel gets too thick, whisk in 1–2 tbsp warm milk to loosen.
• Day-old sourdough holds up better to the sauce and broiler, staying crisp outside and tender inside.
• Broilers vary: keep the door cracked if your oven recommends it and watch constantly to avoid scorching.

Variations

• Classic Monsieur: Skip the fried egg and serve as a Croque Monsieur.
• Mornay Twist: Whisk 1/4 cup (25 g) grated Gruyère into the béchamel to make a Mornay sauce for an extra-cheesy top.
• Cheese Swap: Try Comté or Emmental in place of Gruyère for a slightly different nutty profile.

Storage & Make-Ahead

Make the béchamel up to 3 days ahead; cool, refrigerate in a covered container, and rewarm gently with a splash of milk. You can toast the bread 2 hours in advance and keep at room temperature. Assemble and broil just before serving for best texture. Leftover sandwiches (without the egg) reheat at 350°F (175°C) for 8–10 minutes; add a fresh fried egg after reheating. Not recommended for freezing.

Nutrition (per serving)

Approximate: 900 calories; 45 g protein; 48 g carbohydrates; 60 g fat; 2 g fiber; 1700 mg sodium. Values will vary based on brands and exact portions.