Place a rack in the center of the oven, and preheat the oven to 375°F.
Brush an 8″ or a 9″ square baking pan with a little soft butter.
In a small bowl, stir the baking soda into the boiling water until the soda is dissolved.
Set aside.
Place the molasses and eggs in a large bowl, and stir with a wooden spoon to combine and break up the egg yolks.
Add the ½ cup butter, sugar, flour, ginger, cinnamon, and allspice, and stir well until the mixture is smooth, 40 strokes.
Stir the baking soda and water mixture into the batter until it is smooth, 1 minute.
Pour the batter into the prepared pan, and place the pan in the oven.
Bake until the gingerbread rises and the top springs back when lightly pressed with a finger, 35 to 40 minutes.
Remove the pan from the oven.
Let the gingerbread rest in the pan for 20 minutes before slicing.
Serve warm with a pour of cream.
