Preheat the oven to 220°C/Fan 200°C/Gas 7. Oil a 30 x 20cm baking dish. Put the milk in a saucepan, place on a low heat, bring to a simmer, then take off the heat.
Melt the butter in a medium saucepan on a low heat, then stir in the flour and mustard for a minute until bubbling.
A ladleful at a time, add the warm milk to the pan, stirring for about 5–10 minutes, until the sauce coats the back of a spoon. Stir in most of each of the cheeses, season to taste and take off the heat.
Cook the farfalle in a large pan of boiling, salted water for half the cooking time stated on the packet, adding the cauliflower and broccoli for the final 3 minutes, then drain.
Tip the pasta and vegetables into the sauce, stir together and spoon into the oiled baking dish. Scatter with the remaining cheeses and a grind of pepper, then bake for 20 minutes until golden and bubbling.
Rich, madly cheesy and the perfect bake on a cold day. Serve on its own with lots of black pepper, and maybe a salad, or as a side with roast chicken.