Michelle's Croque Madame – MATHESON

Ingredients

• 2 tbsp butter
• 2 leeks, finely chopped
• 2 tbsp mustard
• ½ tsp lemon zest
• 1 tbsp lemon juice
• Salt and pepper to taste
• 1½ tbsp butter
• 1½ tbsp all-purpose flour
• 1¼ cup milk
• ½ tsp grated nutmeg
• ¼ cup grated Gruyère cheese
• 4–5 tbsp softened butter
• 300g jambon de Paris, thinly sliced
• 4 slices sourdough bread
• ¾ cup grated Gruyère cheese
• 2 eggs
• Fresh thyme or chives