Soak the chickpeas overnight in a large bowl of water.
Rub the aubergine with some olive oil and place it on a baking sheet. Roast in a preheated oven for about 25 minutes until soft, then let it cool. (This step can be done well in advance - but do keep the baked aubergine in the fridge until needed).
Scrape the flesh out of the aubergine and discard the skin.
In a mixing bowl, combine the drained chickpeas, aubergine, spices, tahini, garlic, herbs and chickpea flour. Season with salt and pepper (you can add a pinch of cayenne if you like).
Put half of the mixture into a food processor and whiz, scraping down the sides of the food processor as necessary. When you get a textured mixture, resembling couscous, transfer it into a bowl. Repeat with the remaining chickpea mix, then combine well the two blends. Cover the bowl and chill for 2 hours (or place in the freezer for 20 minutes).
Heat some grapeseed oil in a small, deep pan. The depth of the oil should be about 3 cm. Form the batter into small patties or balls and fry 4-5 at a time for about 2-3 minutes per side, or until golden brown. Add more oil to the pan as necessary.
Transfer the falafels onto a plate, lined with paper kitchen towels.
Serve the falafels warm or at room temperature.