Begin by preheating the oven to 400°. Place 4 paper liners on the outside edge of a cupcake tin.
In a small bowl, whisk together the flour, baking powder, cinnamon, ginger and salt. Set aside.
In a medium bowl, cream the butter and brown sugar together with a mixer. Add the applesauce and vanilla and beat until well-incorporated.
Add half of the flour mixture to the butter mixture and beat lightly. Add 1 tablespoon of milk, followed by the remaining half of the flour mixture; finish with the milk. Don’t over-beat this mixture. Divide the mixture between the cupcake papers and bake for 16-18 minutes, or until a toothpick inserted comes out clean. Set aside while making the glaze.
Now, make the glaze. Peel, pit and dice the plum. Add the plum to a small saucepan along with the sugar, lime juice and cardamom pod. Bring this mixture to a low boil and cook until the plum pieces fall apart and are easily smashed with a fork (10-15 minutes). Fish out the cardamom pod, and pass the mixture through a fine sieve to ensure no seeds remain. Let this mixture cool to room temperature.
Brush about 1 teaspoon of the plum cardamom jam on each cupcake before proceeding. Next, cream together the butter and powdered sugar (starting with the smaller amount of each) in a small bowl. Add the rest of the plum jam to this mixture and beat very well. Taste and add additional butter and powdered sugar to taste. The sweetness and intensity of plums vary greatly, so I’ve left some flexibility to suit your own tastes. When ready to serve, dunk the cupcakes in the glaze.