Set the oven to Gas Mark 6 or 200°C.
Cook the pasta in boiling water for the length of time directed on packet, or until just tender, then drain the pasta well into a colander.
Tip the crème fraîche into the hot pan and place it on the hob to heat, then add most of the cheese, mustard and seasoning and mix until the cheese melts. Return the pasta to the pan and stir well to coat in the sauce.
Divide the mixture between the ovenproof dishes and scatter the cubed bread on top, and then the reserved cheese.
Bake the pasta for about 10-15 minutes, or until the cheese melts and the cubes of bread turn light golden in colour. Serve immediately.
Sue's tip: To save putting on the oven, these can also be browned under the grill, but take care that the bread doesn't burn