Preheat oven to 350°F. Spray three 8 inch cake pans with baking non-stick spray. Line the bottoms with 8 inch parchment circles. Then, spray again. Set aside.
In a mixing bowl, sift the flour, ginger, pumpkin pie spice, cinnamon, and salt. Set aside.
Using a mixer, beat the butter and brown sugar. Mix for 1 minute until light and fluffy. Add in molasses. Scrape the bowl. Add in eggs and egg yolk one at a time. Mix on low until combined. Scrape the bowl and make sure it is all mixed together.
Add in ⅓ of dry ingredients and half of the buttermilk. Mix until starting to combine. Add the next ⅓ of the dry ingredients and the rest of the buttermilk. Mix until just combined. Then, add in the rest of the dry ingredients and mix. Scrape the bowl and beat again on low for 30 seconds.
Pour batter evenly throughout the three cake pans. Use a kitchen scale to make sure it is even. Bake for 18-22 minutes. The cake is done baking when a toothpick inserted comes out clean.
Let the cakes sit in the pans for 10 minutes. Then, transfer to a cooling rack. Allow cakes to cool completely. At this point you can wrap and freeze the cakes if making ahead of time.