Dissolve the yeast and sugar in the water. In a food mixer with dough hook attachment, place both flours, the fermenté and butter. Pour in the yeasty water and mix to a solid dough. Mix on low for 4 minutes. Add the salt, then mix on medium speed for 1 minute. Add the chopped raisins and walnuts and mix to ensure even distribution.
Remove the dough from the mixer, place in a bowl and co