Boil spaghetti in salted water and keep warm. Divide avocado into 2 halves, remove skin and pip and dice avocado flesh. Add chopped chili and mash all. Douse with milk, make a smooth paste and season to taste with salt and pepper. Fry garlic, onion and shrimps about some minutes, season with salt and chopped parsley.
Arrange spaghetti, cover with avocadosauce and place shrimps upon.