This is what you need
75 g mayonaise
75 g creme fraiche
50 g blue cheese
..and this is how you do it
Mix all the ingredients into a bowl and stir until a fine paste. If you are in a hurry; use a hand blender.
Use for whatever type of salad you like, but I can imagine it works all the better if there is something sweet in it, like raisins.
Some blue cheeses taste sharper than others, while still others are rather salty. Roquefort covers both. More cheese if the blue cheese is very mild and vice versa.
(Recipe from Kulinarisk Akademi, Oslo)