30 gmbutter, coarsely chopped1onion, diced1garlic clove, finely chopped1 tbsp eachfinely chopped sage and thyme, plus extra, coarsely torn, to serve1 kgcauliflower (1 small), coarsely chopped250 gmfloury potatoes (such as sebago), coarsely chopped500 ml(2 cups) each milk and chicken stock200 gmcrème fraîcheFinelygrated rind and juice of ½ lemonCheddar toasts100 gmsoftened butter100 gmfinely grated vintage cheddar2 tspthyme4small sourdough rolls, halved
Melt butter in a large saucepan over medium-high heat, add onion, garlic and herbs, season to taste and stir occasionally until light golden (4-5 minutes).
Process cauliflower and potato in batches in a food processor or with a hand-held blender, then add to pan along with milk, stock and 500ml water. Season to taste, cover with a lid, bring to the boil, then uncover and simmer, stirring occasionally, until cauliflower and potato are tender (10-15 minutes). Add crème fraîche, lemon rind and juice, blend with a hand-held blender until smooth, season to taste and keep warm.
For cheddar toasts, beat ingredients except bread rolls in a bowl to combine (1-2 minutes) and season to taste. Spread thickly on rolls and grill until golden and bubbling. Serve hot alongside hot cauliflower soup, scattered with extra herbs.