In a bowl of a stand mixer, add the flour, brown sugar, baking soda, cinnamon, allspice, ginger, and salt.
Whisk to combine.
Add the butter to the flour mixture, and use a pastry blender to blend the mixture until combined.
Place the bowl back on the mixer.
Gradually add the molasses, egg, and milk, and mix on medium speed until combined.
Scrape the sides and mix again until dough ball forms.
Remove the bowl from the mixer and form the dough into a ball.
Cover the bowl and place it in the refrigerator for 30 minutes.
Preheat the oven to 350°F.
Place the dough ball on a lightly floured counter.
Roll out the dough to ½ inch thick.
Using a 3.5" x 2.5 rectangle cookie cutter, cut your cookies and place them on a silicone or parchment paper-lined baking sheet.
Bake for 8-10 minutes.
Place the baked cookies on a cookie rack to cool to room temperature.