Heat the oven to 325F and line a 12-cup muffin tin with paper liners.
Stir the gingersnap crumbs, melted butter, and brown sugar together until the mixture looks like wet sand. Press about 1 tablespoon into each liner and bake for 5 minutes.
Make the Pumpkin Cheesecake Filling
Beat the cream cheese and sugar until completely smooth, scraping the bowl as needed.
Mix in the pumpkin puree, sour cream, vanilla, pumpkin pie spice, and salt until just combined.
Add the eggs one at a time on low speed, stopping as soon as each disappears. Do not overmix.
Fill and Bake
Divide the filling among the liners, filling each nearly to the top.
Bake at 325F for 18 to 23 minutes, until the centers are set with just a slight jiggle. They settle flat as they cool.
Cool, Chill, and Top
Cool in the tin for 10 minutes, then chill at least 3 hours, preferably overnight.
Just before serving, add a small swirl of whipped cream to each and dust with pumpkin pie spice.
Notes
Room temperature matters: soften the cream cheese for an hour to avoid lumps.
Don't overbake: pull them while the centers still jiggle slightly, they finish setting as they chill.
Make ahead: bake and chill up to 2 days ahead, then top with whipped cream the day you serve.
Mini option: use a mini muffin tin for two dozen bite-size cupcakes, baking about 12 minutes.