Add yeast and water to the mixer bowl with a pinch of sugar until frothy (about 5 mintues).
In a separate bowl, combine melted butter, milk, cream, sugar, and salt.
Ensure that the butter mixture is not too hot. It should be warm to the touch, not burning (about 110 - 115 degrees F). Add butter mixture into yeast mixture.
Turn mixer on low speed with a paddle attachment. Add eggs and egg yolk one at a time, followed by about 3 cups of flour.
Switch to a dough hook. Add in raisins and zests, followed by the rest of the flour. Knead with the dough hook for 5 minutes. If you are mixing by hand, knead for 10 minutes while incorporating the flour.
Turn out the dough into a large greased bowl. The dough will be sticky. Cover and let rise for 1 hour.
Punch dough down and turn onto a floured surface. Divide dough into 9 sections. Roll each section into a 12-inch rope.
Braid 4 ropes to make the base. Stack with a braid of 3 ropes. Twist the final 2 ropes and place them on top. Tuck the ends in underneath the loaf. Secure with wooden skewers if you wish. Cover and let rise for 1 hour.
Preheat oven to 400 degrees F. Brush loaf with egg wash. Add slivered almonds if using. Bake for 15 minutes.
Reduce heat to 375 degrees F. Bake for 30-45 minutes until golden brown. You can check to be sure the internal loaf temperature reaches 190 degrees F.
Cool completely. Dust with confectioners sugar before serving.