For the goose breast, pour the chicken stock (or soup) into an ovenproof dish.
Season the goose breast with salt, season with pepper, fill in skin side down. Peel and coarsely chop the onions. Add to the stock with the marjoram, crumbled bay leaves and juniper. Place in the heated oven at 225 °C (gas 4) on the middle rack, basting from time to time with the stock from the pan.
After about 75 minutes, turn the goose breast to the other side and cook for a further 30-45 minutes, bubbling frequently. The skin should be brown and crispy.
Remove the goose breast, degrease the stock and loosen the roasting substances with a brush. Grind the onions in the sauce with a hand blender. Remove the goose breast from the bone, cut it open and bring it to the table.