Heat the oven to 175 C / 350 F with a rack in the center. Grease a 23 x 13 cm / 9 x 5-inch loaf pan and line it with parchment, leaving an overhang on the two long sides.
Dice the peeled pears into 1 cm / 1/2-inch pieces and blot them dry with paper towels. Toss with 1 tablespoon of the measured flour and set aside.
Whisk the remaining flour with the baking soda, baking powder, salt, ground ginger, cinnamon, cloves and nutmeg in a 3-quart / 2.8 L mixing bowl.
In a second bowl, whisk the cooled melted butter, brown sugar and molasses until smooth. Whisk in the eggs one at a time, then the buttermilk, grated ginger and vanilla until glossy.
Pour the wet mixture over the dry and fold with a spatula for about 15 strokes, just until no flour streaks remain. Fold in the pears. The batter will be thick but pourable.
Scrape the batter into the pan, smooth the top and sprinkle with the turbinado sugar. Bake for 55 minutes, tenting loosely with foil at 35 minutes if the top darkens quickly, until a toothpick in a spot without pear comes out with a few moist crumbs and the center reads 205 F / 96 C.
Cool in the pan on a wire rack for 15 minutes, then lift out by the parchment and cool on the rack for another 30 minutes. Slice into 10 slices about 2 cm thick with a serrated knife.