Preheat oven to 350 degrees and lightly grease a 9-inch bundt pan.
In a medium-sized bowl whisk together flour, baking powder, cinnamon, nutmeg, ginger, and salt.
In the bowl of a stand mixer or in a large bowl with a hand mixer, beat butter and granulated sugar on medium speed until pale and fluffy, about 2 minutes.
Beat in eggs, one at a time, until well blended.
Mix in flour mixture in 3 additions, alternating with sour cream.
Spoon half of the batter into the prepared pan.
Pour all of the pumpkin pie filling over the layer of cake batter.
Spoon the remaining batter over the pumpkin pie filling and gently spread with a spatula. If your batter doesn't completely cover the pie filling, that's OK. The cake will expand and rise as it bakes.
Bake at 350 degrees for about 45 minutes, until a toothpick inserted into the top cake layer comes out clean.
Remove from oven and jiggle gently to loosen edges of cake from pan (if this doesn't work, you can gently use a spatula). Place upside down on metal rack and let cool for about 10 minutes. Then lift bundt pan from cake and let cake remain on rack to cool completely.
Once cake has cooled, pour sour cream icing over the top of the cake, letting it drizzle down the sides. Top with sprinkles if desired.