In a large heavy based saucepan/dutch oven, melt the butter over low heat & fry the leek for 2-3 mins, or until soft.
25 g salted butter, 1 medium sized leek (white part only)
Once leek is soft, add garlic & stir for 30 secs, then stir through milk. Add cauliflower & potatoes then bring to a simmer.
1 kg cauliflower, 4 garlic cloves, 750 ml milk, 300 g potatoes
Simmer, partially covered for 15-18 mins, or until cauliflower & potatoes are tender. Remove from heat.
Using an immersion/stick blender, blend soup until smooth (see notes) and check for seasoning.
salt & pepper to taste
Divide soup between serving bowls, top with fresh parmesan, thyme and drizzle with olive oil if using, and serve with fresh parmesan on the side for each guest to add as they wish (see notes).
fresh thyme leaves to garnish, olive oil to garnish, 60 g fresh parmesan