For the muffins:
Preheat the oven to 350˚ F. Line muffin pans with paper liners. In a medium bowl, combine the flour, baking soda, salt and spices. Whisk to blend. In a mixing bowl, combine the butter and sugar. Beat on medium-high speed until light and fluffy, about 2 minutes. Blend in the eggs one at a time. Mix in the molasses.
With the mixer on low speed, stir in half of the dry ingredients just until incorporated. Add in the second half, again mixing just until incorporated. Mix in the water on medium-low speed, just until evenly mixed and no lumps remain.
Divide the batter between the prepared muffin liners, filling each about two-thirds of the way full. Bake, rotating the pans halfway through, until the tops are set and a toothpick inserted in the center comes out clean, about 18-20 minutes. Transfer to a wire rack to cool.
To finish, combine the sugar and cinnamon in a small bowl and whisk until evenly combined. Dip the top of a muffin in the melted butter, then into the cinnamon-sugar mixture to coat with a thin layer. Repeat with the remaining muffins. Serve warm.