Preheat oven to 250°C fan forced. Lightly grease 2 roasting pans. Place the pumpkin and mushrooms in separate bowls.
Combine the maple syrup and 3 tablespoons oil in a jug. Season with salt and pepper. Pour half over the pumpkin and half over the mushrooms. Stir to coat. Spread pumpkin over the base of 1 pan and mushrooms over the other. Place pumpkin on top shelf of the oven and the mushroom below. Roast for 15 minutes.
Remove the mushrooms and set side. Turn the pumpkin over and roast for a further 5–10 minutes or until golden and tender. Set aside 10 minutes.
Meanwhile, cook the risoni in a saucepan of boiling salted water, following packet directions. Drain and transfer to a large bowl. Combine the lemon juice, mustard, remaining oil and salt and pepper and pour over the warm risoni, stir to combine.
Add the pumpkin, mushrooms, chickpeas, rocket and hazelnuts. Taste, adjust the seasoning and toss to combine. Serve warm or at room temperature.