1.Preheat oven to 200°C (180°C fan forced).
2.Using your hands, break the broccoli into small florets.
3.Half-fill a large saucepan with water, put a lid on the pan. Heat on the stove over high heat until the water boils. Add the pasta, cook, uncovered, until it is tender (check the instructions on the packet for how long this should take). About 3 minutes before the pasta is ready, add the broccoli, cook for another 3 minutes. Place a colander over a large heatproof bowl in the sink. Pour the pasta and broccoli into the colander, reserve about ¼ cup of the cooking liquid in the bowl and drain the rest down the sink. Return pasta and broccoli to the pan.
4.Meanwhile, drain the tuna, add to the pasta with the cream, lemon rind, lemon juice and 2 tablespoons of the cooking liquid from the pasta. Season with salt and pepper; mix well. Spoon the pasta mixture into four 2-cup (500ml) ovenproof dishes, sprinkle with the cheese.
5.Place the dishes on an oven tray, place into the oven and bake for about 30 minutes or until the cheese has melted and the top is golden brown.
6.Cut the lemon into wedges, serve alongside the pasta bake.