Preheat the grill on high. Heat a large sauté pan and add the butter, once melted add the flour and cook for 2 minutes. Gradually add the milk until it comes to a smooth sauce. Add the mustard and Worcestershire sauce and grated cheese, whisk until smooth. Meanwhile place the broccoli in a large saucepan of boiling water and cook for 2-3 minutes, drain and place in an oven proof dish. Heat the butter in a medium frying pan and add the brioche, cook for 2 minutes until golden brown. Layer the broccoli, sauce and brioche and sprinkle over the poacher cheese and place under a grill. Place the leaves in a medium glass bowl and in a separate bowl whisk the oil, vinegar and lemon juice, pour over the salad. To serve Remove from the grill and serve warm with the salad on the side.