The night before, put apricots and orange juice in a bowl and set aside.
To make the dough, put flour, 1 tsp salt, butter, milk, yeast and egg in a bowl, and mix together to form a dough. Turn the dough out onto a lightly floured surface and knead for 6 mins.
Transfer dough to a mixing bowl. Cover, then set aside to rise in a warm place for 1 hr.
Meanwhile, drain the apricots. In a mixing bowl, cream the butter and muscovado sugar until fluffy. Mix in the apricots, flour, raisins, walnuts and orange zest.
Turn the risen dough out onto a lightly floured surface. Roll it out to a rectangle, about 25 x 33cm. Evenly spread over the apricot mix, then roll out the marzipan and lay it on top. Roll up the rectangle tightly so it looks like a Swiss roll. Roll slightly, then cut lengthways along the roll, leaving 1 end joined. Twist 2 lengths together, then shape into a ring on a baking sheet lined with baking parchment. Set aside to rise for 1 hr.
Heat oven to 200C/180C fan/gas 6. Bake the twist for 30 mins until risen and dark golden. Towards the end of the baking time, gently warm the apricot jam in a small pan. Brush the freshly baked loaf with the warm jam to glaze it, then set it aside to cool. Once cooled, drizzle the twist heavily with the runny icing.