Crispy shallot cauliflower cheese

Ingredients

• 1 large or 2 small cauliflowers
• 1 tbsp olive oil
• ½ tsp salt
• ½ tsp pepper
• 4 tbsp butter
• 2 round shallots, finely chopped
• 4 tbsp flour
• 500ml whole milk
• 2 tsp Dijon mustard
• 250g extra mature Cheddar cheese
• 2 tsp olive oil
• 2 round shallots, finely sliced
• 120g breadcrumbs
• Fresh thyme
• Zest of 1 lemon
• 100g Parmesan cheese, grated
• Salt and pepper, to taste