Macaroni cheese with a crunchy topping

Nut topping

• 1 lemon, zest only, no white pith
• 100 g Parmesan cheese, crust removed and cut into cubes (3 cm)
• 2 slices bread (approx. 70 g), torn into pieces
• 1 sprig fresh rosemary, leaves only
• 50 g raw almonds
• 70 g unsalted butter
• 20 g pepita seeds (optional)
• 20 g sunflower seeds (optional)
• 1 pinch sea salt
• 1 pinch ground black pepper

Macaroni cheese

• 60 g unsalted butter, plus extra for greasing
• 90 g Gruyère cheese, cut into cubes (3 cm)
• 50 g Parmesan cheese, crust removed and cut into cubes (3 cm)
• 60 g leek, white part only, cut into pieces
• 200 g cauliflower, cut into florets
• 150 g sweet potato, peeled and cut into cubes (2 cm)
• 1200 g water
• 300 g macaroni pasta
• 50 g plain flour
• 500 g full cream milk
• ¼ - 1 tsp ground nutmeg, to taste
• 1 tsp paprika, to taste
• 2 tsp Dijon mustard
• 1 pinch sea salt, to taste
• 1 pinch ground black pepper, to taste