75²µ/2Β½΄Η³ϊ caster sugar
12g fine sea salt
625g/1lb 6oz strong white bread flour, plus extra for dusting
40g/1Β½oz fresh yeast
500g/1lb 2oz chilled unsalted butter, plus extra to serve
1 free-range egg and 1 egg yolk, lightly beaten
raspberry jam, to serve