Prepare a 12-cup muffin pan (or two 6-cup muffins pans) with liners, or skip the liners and just grease the cups.
In a medium bowl, whisk together the flour, baking powder, cinnamon, ginger, nutmeg, allspice, and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl, cream the butter and sugar until light and fluffy, 1 to 2 minutes.
Add the eggs one at a time, beating after adding each one.
Add the pumpkin purée and vanilla extract.
Stir in half the dry ingredients, mixing until just combined. Add the second half. Do not overmix.
Spoon the batter into the prepared muffin cups so they are 3/4 of the way full.
Bake for 18 to 22 minutes, until a tester comes out with few crumbs.