Two thick leeks cut in half widthways 2 tablespoons water 25g butter 25g plain flour pepper 1 teaspoon made mustard 300ml milk 50g finely grated cheese (like Leicester) 4 slices cooked ham Toasted crumbs Tomato slices, to garnish Arrange leeks in an ovenproof dish . Add the water, cover and cok in microwave for 7 minutes. Sauce: Place the butter and let melt in microwave. Stir in the flour, pepper, mustard, then gradually add the milk, stirring well. Cook until smooth and thickened. beat in the grated cheese. Drain the leeks and roll one slice of ham around each half. Pour the sauce over the leeks and ham, sprinkle with toasted crumbs and arrange tomato slices on top. Cook for another 5 to 7 minutes and serve.