Preheat oven to 325°F.
Butter 2 9-inch layer cake pans, and line bottoms with wax paper.
Sift together whole wheat pastry flour, unbleached white flour, baking powder, and spices 3 times.
In a large bowl, cream butter until fluffy.
Beat in honey and then egg yolks.
Add about one-third of the flour, blending well.
Beat in milk.
Add another third of the flour, then yogurt, and vanilla.
Add remaining flour.
Blend well after each addition.
Divide batter between the 2 prepared pans.
Sprinkle mango over top, and press down just to surface of batter.
Bake layers on middle shelf of oven for 40 to 45 minutes or until golden brown and beginning to shrink away from sides of pan.
Layers will be moist.
Cool for 5 minutes, then carefully remove from pans, peel off wax paper, and turn right-side up.
Spread Vanilla Cream between layers.
Sprinkle date sugar on top, if desired.