Combine the yeast, along with 1 teaspoon of the caster sugar and 125ml milk in a large bowl and whisk until dissolved. Measure then sift in 75g of the flour then cover and allow to stand in a warm place for about 40 minutes or until mixture has doubled in size.
Meanwhile, beat the butter and vanilla extract along with the remainder of the sugar and the salt in a small bowl with an electric mixture until light and creamy. Beat in the eggs one at a time. Gradually add the wet mixture and the remainder of the flour into the yeast mixture in two batches.
Turn the dough out onto a floured surface and knead for about 10 minutes, or until smooth and elastic. Place dough in large greased bowl, cover and allow to stand in a warm place for about 1 1/2 hours or until doubled in size.
Preheat the oven to 200 C / Gas 6. Grease a 21cm kugelhopf (ring) cake tin.
For the filling;
Meanwhile, make a walnut filling by combining the butter, milk and coffee. Mix well then add the walnuts, sugar, lemon rind, breadcrumbs, mixed spice and ginger and mix well.
Turn dough onto floured surface, knead until smooth. Roll dough to 20x40cm rectangle, spread walnut filling over dough, roll up from one end (as for Swiss roll). Brush the end of the roll with water.
Place the roll in the prepared kugelhopf tin with the seam towards the centre. Gently press dough firmly into the tin and press ends together to join. Cover the pan and allow to stand in warm place until dough is risen to within 1cm from rim of the pan.
Reduce the oven temperature to 180 C / Gas 4 just prior to placing the cake in the oven to bake.
Bake in the preheated oven for 40 minutes until risen and golden brown. Remove from the oven and allow to cool fully. Serve dusted with icing sugar if desired.