1 tsp Dijon mustard
500g/1lb 2oz dried macaroni
100g/3½oz plain flour
1 bay leaf
salt and freshly ground black pepper
60g/2¼oz white breadcrumbs
pinch freshly grated nutmeg
100g/3½oz butter, plus extra for greasing
400g/14oz mature cheddar, grated
75ml/2½fl oz double cream
1.2 litres/2 pints full-fat milk
50g/1¾oz Parmesan, grated
100g/3½oz smoked bacon lardons or smoked pancetta cubes