White Sauce: Melt the butter in a saucepan over medium heat then add the flour and cornflour. Quickly stir until smooth. Add the cold milk all at once and cook on low heat stirring frequently until thick. If you start seeing some lumps in the sauce then use a whisk to smooth them out. Season with salt and pepper and set aside.
Lentils: Rinse the lentils and remove any foreign bodies. Add the lentils to a pressure cooker. Add some salt, seal the cooker and cook on low heat for 20 minutes after it starts whistling. Let the cooker depressurise before opening it.
Preheat the oven grill.
Bake: Grease a large baking dish. Mix the lentils and the white sauce then pour the mixture into the tin.
Push the eggs into the lentils so that they are covered.
Sprinkle with grated cheese and grill for a few minutes or until golden on top.