Clean and shine the mushrooms. Heat the fat in a pan. Wash the prawns, dab dry and fry for 2-3 minutes on each side. Season with salt and pepper. Remove from the pan and keep warm.
Peel the garlic and cut it into slices, except for one clove. Fry briefly in the cooking fat over medium heat. Add mushrooms and cook for 8-10 minutes. Add prawns at the end and season everything with salt and pepper.
Mix the sour cream, mayonnaise and milk. Press the remaining clove of garlic through a garlic press and add to the sauce. Season to taste with salt and pepper. Arrange mushrooms and garlic sauce in small pans and serve garnished with basil as desired.