In a medium bowl, add flour, ginger, ground cinnamon, nutmeg, cloves, salt, and baking soda.
In another large bowl, combine together melted butter, brown sugar, and molasses. Whisk in egg, milk, and vanilla extract until they are well-combined.
Add the dry ingredients to the wet ingredients. Carefully mix until just combined.
Use a cling wrap and cover the bowl. Put it in the fridge for at least 1 hour. Preferably up to 12 hours.
Preheat oven to 350ºF. Scoop 1 tablespoon of chilled dough. Roll into a ball. Ensure that cookie balls are placed 2 inches apart on the prepared baking sheet.
Bake balls for around 10-15 minutes, until they are puffed and just set. Let whoopies cool completely before you start frosting.
Beat together cream cheese and butter until fluffy. Add powdered sugar and vanilla extract. Whisk until well combined. This forms the frosting.
Spread or pipe about 2 teaspoons of filling onto the bottom of a cookie. Top with another cookie, forming a sandwich. Repeat with remaining cookies.
Chill for 30 minutes. Dust chilled whoopie pies with powdered sugar, if desired. Enjoy!