Grease a 20cm square, shallow cake tin with butter and line with baking parchment.
In a large bowl, sift together the flour and salt, then stir in the yeast and caster sugar.
Using your fingertips, rub the butter into the flour mixture until it resembles breadcrumbs.
Tip the milk and the egg into a medium bowl, and mix until well combined. Using a palette knife, stir into the flour mixture, a little at a time, until a soft dough is formed. You may not need to use all the liquid.
Place the dough on a lightly floured surface and knead for 10 minutes, until the dough is smooth and elastic. Roll out to a 35 x 25cm rectangle.
For the filling, in a small bowl, mix together the dried fruit, spice and muscovado sugar.
Leaving a 2cm border around the edge of the pastry rectangle, brush the dough with the melted butter. Scatter over the fruit mixture and roll up the dough from the long side, like you would a Swiss roll. Cut into 9 equal slices and place in the cake tin, 3 in a row, cut-side up. Leave a little space between each slice to allow the dough to rise. Cover with lightly oiled clingfilm and leave in a warm place until well risen (about 45 minutes).
In the meantime, preheat the oven to 200°C, fan 180°C, gas 6. 9 Bake in the oven for 25–30 minutes, until golden. For the topping, drizzle with the honey and sprinkle over the caster sugar. Leave to cool slightly, then pull the buns apart and serve warm.