Cook the pasta as usual in salted water until al dente.
In the meantime, carefully fry the spring onions in a large pan with a little olive oil. Add the crabs and their brine. Mix the sour cream, cream cheese and milk and also add. Let it reduce slowly, the sauce shouldn`t be too runny. Season with salt and pepper.
Mix the drained noodles in the pan with the sauce, then fold in the quartered cocktail tomatoes, heat everything quickly and serve immediately.