1 garlic clove, finely grated
1 small onion, finely chopped
2 medium–large cold leftover baked potatoes, cut in half, flesh scooped out and skins reserved
2 spring onions, finely sliced, to garnish
salt and freshly ground black pepper
2 tsp olive oil
400ml/14fl oz vegetable stock
20g/¾oz butter
20g/¾oz cheddar, finely grated, plus extra to serve
100ml/3½fl oz full-fat milk (or cream for extra creaminess, or a mixture of both)