Cauliflower cheese pasta bake

Name: Cauliflower cheese pasta bake
Ingredients: 1 cauliflower, broken down into florets, core sliced, leaves removed and reserved, thick stems sliced; 2 tbsp olive oil; 6 shallots, sliced; 1 tsp caster sugar; 1 thyme sprig; 2 tbsp white wine; 100g large pasta shapes, such as conchiglioni; 20g butter; 1 bay leaf; 2 tbsp plain flour; 600ml milk; 100g mature cheddar; 50g parmesan (or vegetarian alternative), plus extra to top; nutmeg, grated; 50g gruyère or comté; 1 tsp white wine vinegar or lemon juice