For many years now I have been making smoked fish and cream cheese spread. It couldn't be simpler. Buy a packet of smoked mackerel (or herring) and a tub of cream cheese (fromage à tartiner). Cut the fish into chunks and put it and the cheese in a jug. Whizz together with the stick blender. Serve spread on crackers or baguette.
Mélange de hareng fumé doux et fromage frais.In my experience the ratio of fish to cheese can be fairly flexible. You can use the mackerel that is sold with a peppercorn coating if you wish. It freezes well. If you are concerned about fat content, buy low fat (léger) cheese. Cow's milk or goat's milk cheese both work well with smoked fish.