Heat butter and milk over low on the stovetop until butter has melted. Cool to lukewarm.
In a large bowl, dissolve the yeast in the warm water and beat in the egg yolk.
Blend in the cooled milk mixture.
Sift in the flour, salt, and Beat until the mixture is smooth and creamy.
Cover bowl and refrigerate overnight.
The next day, blend walnuts, raisins, milk and apple butter in a saucepan over medium-low.
Stir until the mixture thickens and then let cool.
Beat egg whites until stiff and slowly add in the 1 cup of sugar. Fold into the cooled apple butter walnut mixture.
Spray bread pan with non-stick cooking spray.
Divide dough into two equal pieces (4 if using 2 small bread pans) and dust each with flour.
Roll out (one at a time) to make a large circle. Pour half of the walnut filling onto the dough and spread out over the dough and roll up like a jelly roll. Set aside.
Roll out second piece of dough and repeat the process. When done, twist the two pieces of filled dough together, making a braid or twist. Place in carefully in bread pan.
Place on stovetop and let rise for 30 minutes while preheating the oven to 350 degrees.
Bake for 40-45 minutes.
Cool in pan for 15 minutes and then invert to a cake plate.
Notes
Drizzle with a vanilla glaze, if desired.Serve fresh for best results, or reheat slices in microwave for 30 seconds prior to serving to retain moistness.