Preheat your oven to 400 degrees F. Pre two 8-inch round baking pans with nonstick spray (or three 6-inch if you're doing 6-inch cake layers), parchment paper and spray again. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment cream the butter and sugar until light and fluffy, about 2 minutes.
Add the eggs, pumpkin puree, and vanilla. Beat until blended. Don't worry if it looks curdled. It will come back together once you add the flour.
In a separate bowl, combine the flour, baking powder, salt and pumpkin pie spice (or spices to create pumpkin pie spice). Whisk to combine. With the mixer on low speed, add the flour mixture to the butter mixture and mix until just incorporated.
Cover and refrigerate for at least one hour.
Measure out 10 ounces of dough for each of the two 8-inch cake pans. Using your hands, push the dough out to the edge of the pan (doesn’t need to be touching, just try to create an even circle).
Bake the two large cookies for 7 to 8 minutes. When you take the cookies out, they shouldn’t be light in color, barely golden brown. We want the cookie to come out still light in color so it’s nice and soft in the cake. Cool completely before frosting.