Preheat oven to 375°F (190°C). Line baking sheets with parchment paper.

Cream together softened butter and brown sugar until light and fluffy using an electric mixer.

Beat in the molasses and egg until well combined.

In a separate bowl, whisk together the flour, baking soda, ginger, cinnamon, cloves, allspice, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Stir in crystallized ginger, if using.

Cover the dough and refrigerate for at least 30 minutes (or up to 2 days).

Roll out dough to ¼ inch thickness on a lightly floured surface. Cut out cookies using cookie cutters. Reroll scraps.

Place cookies onto prepared baking sheets, leaving about 1 inch between each. Bake for 8-10 minutes, or until edges are firm and lightly golden brown.

Let cookies cool on baking sheets for a few minutes before transferring to a wire rack to cool completely.