Preheat oven to 350°F.

Brush a 10-inch cast iron skillet or 8x8-inch glass baking dish with melted butter.

In a medium bowl, whisk together whole wheat pastry flour, all-purpose flour, ground ginger, ground cinnamon, baking powder, baking soda, and salt.

In a separate bowl, beat egg, sugar, and molasses with a mixer for 3 minutes until light and fluffy.

Add applesauce and oil to the egg mixture and beat until blended.

Gently fold the flour mixture into the wet ingredients until just combined.

Fold in the yogurt until well combined.

Press brown sugar evenly over the bottom of the prepared skillet or baking dish.

Sprinkle chopped walnuts over the brown sugar.

Arrange thinly sliced pear slices in concentric circles over the nuts.

Pour the gingerbread batter evenly over the pears.

Bake for 35-40 minutes, or until a toothpick inserted into the center comes out clean.

Loosen the edges of the cake from the skillet or dish with a knife.

Invert the cake onto a serving platter.