Allow the shrimp to thaw completely. Rinse them with cold water and drain. Add salt and pepper.
In a pan, melt half the garlic butter. Add the shallots and saute until they take on color. Add the shrimps and stir to bring to a boil. Pour over the ouzo and add a spoonful of parsley. Bring the ouzo to a boil to evaporate the alcohol. Add the rest of the butter and mix. Leave for a few minutes on medium-low heat until the prawns are cooked. If you see that the pan is too dry then add 1-2 spoons of water.
Sprinkle with the remaining parsley and serve immediately.