Preheat the oven to 350º F. Line a muffin pan with cupcake liners.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, and allspice. Set aside.
In a separate medium bowl, whisk together milk and vinegar. Let the mixture stand at room temperature for 5 to 10 minutes. When it is ready, the milk will be slightly thickened, and you will see small curdled bits. Set aside.
Beat with an electric mixer the butter and brown sugar on medium speed until creamy. Add molasses and vanilla, scraping down the sides and bottom of the bowl as needed; mix to incorporate. The mixture will be piecey and not fully combined. That’s ok.
Reduce mixer’s speed to low. Add half of the flour mixture; mix to incorporate. With the mixer running slowly pour the milk mixture, then add the remaining flour mixture. Mix until just combined. Scrape down the sides and bottom of the bowl as needed.
Spoon the batter into liners, filling 2/3 of the way full.
Bake for about 18 -20 minutes, or until a toothpick inserted in the center comes out clean. Allow the cupcakes to cool completely before frosting.