Brush the aubergines and garlic with oil, season with salt. Wrap the aubergines tightly in foil.
Charcoal/gas/electric grill: Grill the aubergines over/on a medium heat (approx. 200 °C for approx. 30 mins. on all sides. Grill the lemon halves (cut side down) alongside for the final 5 mins.
Scrape the aubergine flesh away from the skin using a spoon, transfer to a blender along with the garlic cloves, chickpeas and remaining ingredients, puree until smooth.
Combine the oil and marjoram. Thread the grilled cheese onto the skewers, brush with half of the oil.
Grill the cheese over/on a medium heat (approx. 200 °C for approx. 4 mins. on each side. Drizzle the remainder of the oil over the hummus, serve with the grilled cheese.