Salted muscovado and hazelnut fudge

1.Preheat oven to 180C. Melt 10gm butter and combine in a bowl with nuts and ½ tsp sea salt. Toss to combine, spread on an oven tray, roast until browned (4-5 minutes) and set aside to cool.

2.Melt remaining butter in a large saucepan over low heat, add sugars, milk, sour cream, vanilla and 120ml water. Increase heat to high, stir until sugar dissolves, then cook without stirring, brushing down sides of pan occasionally with a wet pastry brush to remove sugar crystals, until mixture just reaches 140C on a sugar thermometer (12-15 minutes), or until a little mixture dropped into iced water forms a firm but malleable ball. Remove from heat, dip base of pan in cold water to cool, then, when base of pan is just cool enough to touch, add 1 tsp sea salt flakes and beat with a wooden spoon until thick and grainy (3-4 minutes). Quickly transfer to a lightly oiled 20cm-diameter cake tin lined on the base with baking paper and smooth top with a wet palette knife. Scatter with hazelnuts and extra sea salt and stand at room temperature until cool and set. Cut into wedges and serve.