Heat oven to 350F. Prepare three 8-inch cake pans with non-stick spray and parchment rounds. In a medium bowl, whisk together the cake flour and baking powder.
In the bowl of your stand mixer, beat the butter and sugar until light and fluffy. Add in salt and oil, and mix to combine. Scrape down the sides of the bowl.
While the mixer is on low, add in the eggs and egg yolks one at a time, mixing until well incorporated.
With the mixer on low, add in flour, in three additions, alternating with sour cream. Mix in the vanilla, pineapple, and butter extracts. Scrape down the sides to incorporate.
Divide the batter between the cake pans, and bake for 30 minutes, or until a cake tester inserted into the middle of the cake comes out clean.
Cool in pans for 10 minutes, then turn out onto wire rack to cool completely.