Slice the top of the garlic bulb. Cover with foil and place on a roasting tray. Prick the eggplants all over with the prongs of a fork. Rub with olive oil and place on the roasting tray.
Roast in the oven until the eggplants are very soft – about 30 minutes.
Set aside to cool slightly. Scoop out all the flesh from the eggplant and pop the garlic out of the skins. Blend the eggplant and garlic in a food processor until you have a coarse consistency.
Fold in the cumin and lemon juice. Season to taste with salt and freshly ground black pepper.
Spoon the baba ganoush into a serving dish and scatter with the toasted pine nuts. Finish with a drizzle of olive oil and serve at once.