Preheat the oven to 220°C/gas mark 8 and place an oven rack in the centre.
Place the aubergine on a greaseproof paper-lined baking tray. Drizzle with olive oil and season with salt and pepper. Roast for 20 to 25 minutes until golden brown. Set aside to cool.
In the bowl of a food processor, combine the cooled aubergine, beans, parsley, lemon juice, garlic, salt and pepper. Pulse until the mixture is coarsely chopped. With the machine running, gradually add olive oil until the mixture is creamy. Season with more salt and pepper, to taste.
Place the hummus in a dipping bowl and serve with the cucumber slices. Alternatively, spoon the hummus over the cucumber slices and arrange on a serving platter.