1. To make the crêpes, process all of the ingredients in a blender until smooth. Let the mixture stand for 30 minutes.

2. Lightly grease the frying pan with melted butter. Add about 3 tbsp of the batter to the pan, and tilt and swirl the pan so the batter covers the bottom. Cook until the underside is golden brown. Turn the crêpe and cook until the other side is golden. Transfer to a plate. Repeat with the remaining batter, buttering the pan as needed. You should have 12 crêpes. Separate the crêpes with pieces of wax paper.

3. To make the filling, melt the butter in a frying pan over medium heat. Add the mushrooms and cook 6 minutes. Transfer to a bowl. Add the spinach and ¼ cup of the bèchamel sauce. Season with nutmeg, salt, and pepper.

4. Preheat the oven to 375°F (190°C). Divide the filling among the crêpes. Roll them up and place in a shallow buttered baking dish. Stir the Cheddar and mustard into the remaining sauce and season with salt and pepper. Spread over the crêpes. Arrange the tomato on top and sprinkle with the Parmesan. Bake for 30 minutes, or until bubbling and browned.

Variation:

Spinach and Ricotta Crêpes:

Replace the mushrooms with 10oz (300g) ricotta cheese. Add to the cooked spinach and fill the pancakes.