Melt butter in a saucepan over medium heat. Slowly add the flour, until combined

Add milk and whisk constantly until the sauce is well combined. Cook and continue to stir for another 5 minutes until the sauce is thick and glossy and coats the back of a wooden spoon

Stir through the cheese and mustard. Season to taste. Transfer to a bowl

Preheat the oven to 200°C (180°C fan forced). Slice off the top crust layer of the loaf. Place the loaf on it's side and cut lengthways down the centre of the loaf

Spread the bottom side of the loaf with Dijon mustard. Top with a layer of ham slices, and a layer of spinach leaves. Drizzle over 1/2 of the bechamel sauce and top with 1/2 of the cheese

Place the top on the loaf. Transfer to a baking paper covered tray. Spread remaining bechamel sauce on the top layer of the loaf. Sprinkle over cheese and transfer to the oven for 10-15 minutes or until cheese is golden and loaf is toasted

Slice the loaf in triangles and serve