Heat oven to lowest setting.
Place grated ginger on parchment covered baking sheet.
Bake, stirring often, until thoroughly dry.
Turn oven off and on as needed, or prop door slightly open with a wooden spoon. If ginger begins to brown, turn off oven and let it dry with the residual heat. This may take up to 2 hours, depending on how juicy the ginger is.
Toast the cinnamon sticks and nutmeg, in a skillet over medium low heat, for about 3 minutes. Be sure to stir frequently!
Add allspice and cloves and continue to toast for 2-3 minutes, until very fragrant. Remove pan from heat and immediately pour spices onto a plate to cool.
Once cool, finely grate the nutmeg into a small bowl.
Using a coffee or spice grinder, grind the remaining spices in several batches. Be prepared – this may make a lot of noise! Sift spices through a fine sieve into the bowl with the nutmeg.
Put any large pieces left in the sieve back into the grinder and grind again
Repeat as necessary. If there are some small, stubborn pieces that won’t grind, dispose of them.
Whisk together the spices and store in small bottles or sealed bags in a dark, cool location.