500 mlcrème fraîche, chilled100 gm (¼ cup)fine sea salt24small potatoes such as Dutch cream, scrubbed2 tbspolive oil2 tbspchives, finely chopped
Whisk crème fraîche in an electric mixer on medium speed until butterfat and buttermilk separate, then drain (discard buttermilk). Add 125ml iced water, mash with a fork and drain. Repeat until water is clean. Stir in 60gm salt and refrigerate until required. Makes 1½ cups butter. Butter will keep refrigerated for 5 days.
Preheat oven to 190C. Place potatoes in a bowl, drizzle with oil, add remaining salt, toss to combine and transfer to a roasting tray. Roast until golden and cooked through (45-55 minutes), then set aside to steam (5 minutes). Cut a cross on top of each potato, top with whipped cultured butter and chives, season to taste and serve.