Preheat the oven to 350°F (175°C). Grease two standard muffin tins thoroughly to prevent sticking.
Combine dry ingredients:
In a medium bowl, sift together the flour, cocoa powder, baking powder, baking soda, salt, and all spices (cinnamon, cloves, nutmeg, allspice, ginger, and white pepper). Ensure the mixture is evenly combined.
Cream butter and sugar:
In a large mixing bowl, beat the softened butter with the brown sugar until light and fluffy. Add the eggs one at a time, mixing well after each addition. Incorporate the molasses and buttermilk until fully blended.
Incorporate dry mixture:
Gradually add the sifted dry ingredients into the wet mixture, stirring gently until just combined. Avoid overmixing to maintain a tender crumb.
Add liquid and raisins:
Stir in the hot water, followed by the raisins. The batter will appear thin but will bake into a moist texture.
Fill and bake:
Divide the batter evenly among the prepared muffin tins, filling each cup slightly more than halfway. Bake for 20–24 minutes, or until a toothpick inserted in the center comes out clean.
Prepare the icing:
In a small bowl, whisk together powdered sugar, vanilla extract, and water until smooth and pourable.
Finish the muffins:
While the muffins are still warm, drizzle the icing over the tops, or dip the tops directly into the icing for a glazed finish. Allow to set before serving.
Notes
To make Sailor Jacks Spice Muffins gluten-free, substitute the all-purpose flour with a certified 1:1 gluten-free baking blend. Confirm that baking powder, baking soda, and powdered sugar are certified gluten-free to avoid cross-contamination.