Prepare your sprouts by cutting off the end of the stalk, removing a 2-3 of the outer leaves and halving or cutting into quarters, depending on their size.
Place the sprouts in a large roasting tin, sprinkle over the chopped bacon and add the olive oil and maple syrup. Stir well to coat and arrange in a single layer.
Roast in the centre of the oven for 30-40 minutes, stirring after 15 minutes.
Add the coarsely chopped hazelnuts for the final 10 minutes of cooking.