Preheat the oven to 325°F (165°C). Divide 14 paper muffin liners evenly between 2 standard muffins pans.
In a large bowl, whisk together the melted butter and the eggs. Add the buttermilk, molasses, brown sugar, and vanilla and whisk until smooth.
In another large bowl, whisk together the flour, baking powder, baking soda, salt, ground ginger, cinnamon, allspice, cloves, and black pepper. Stir in the chopped crystallized ginger.
Add the flour mixture to the butter mixture and use a rubber spatula to carefully fold together until just combined. Be careful not to overmix, or your muffins will be tough. The batter should still have a couple of streaks of flour.
Divide the batter equally among the prepared muffin pans. Because these muffins have a lot of moisture, they are prone to collapsing a bit in the center. To prevent this, do not fill the muffin wells more than two-thirds full and do not open the oven to rotate the pans during baking.
Bake for 18 to 22 minutes or until a wooden toothpick or skewer inserted into the center comes out clean with only a few dry crumbs clinging to it (as opposed to wet batter).
Remove the muffins from the oven and let cool in the pan for 5 to 10 minutes. Carefully lift the muffins from the pan and transfer them to a wire rack to cool a little more.
Dust the tops with confectioners’ sugar just before serving, if desired.
If you don't have buttermilk you could substitute plain yogurt, sour cream, or regular milk mixed with a teaspoon of lemon juice instead.
If you have a little extra batter or choose to make 12 muffins instead of 14, use the extra batter to make pancakes.