Preheat the oven to Gas Mark 4, 180ºC (350ºF). Cook the macaroni in a large pan of boiling salted water for 10-12 minutes until just ‘al dente’ (tender but still firm to the bite).
Place the crème fraîche in a bowl and beat in the egg yolks and mustard, then season to taste.
Drain the pasta and return to the pan. Stir in the crème fraîche mixture with the cheese, then gently fold in the cherry tomatoes and ham.
Tip the macaroni mixture into an ovenproof dish. Bake for 15-20 minutes until golden brown and bubbling. Leave to stand for a few minutes and then serve straight from the dish with a large bowl of salad.