Preheat oven to 325°F and place racks on top third and bottom third positions.
Prepare three 8-inch cake rounds with parchment paper, then spray liberally with nonstick baking spray.
In the bowl of your stand mixer, add oil and butter and beat for 2 minutes on high speed. Slowly add in sugar and zest and beat on high speed for an additional 4-5 minutes until very pale and fluffy.
Next, add eggs one at a time, combining well after each addition and scraping down the sides of the bowl as needed.
In a medium bowl, combine flour, baking powder, baking soda, and salt. Reduce the mixer speed to low and slowly add the dry ingredients in two increments. Batter will be thick; do not overmix.
Lastly, add sour cream, milk, orange juice, and coconut extract and mix until just combined, scraping down the sides of the bowl as needed.
Evenly divide cake batter into each prepared pan, then bake for 22-25 minutes, or until an inserted toothpick comes out clean with a few moist crumbs attached. Rotate and revolve the cakes halfway through baking.
Remove cakes from the oven and let cool in pans for 15 minutes. Invert cakes onto wire rack until completely cool, about 30 minutes.