Adjust the oven rack to lower-middle position and preheat oven to 325°F.
Line 2 (if making a 4-layer cake) and 3 (if making a 3-layer cake) 8x3-inch aluminum cake pans with parchment and spray with nonstick cooking spray.
Sift the flour into a large mixing bowl; set aside.
4 cups bleached cake flour
Add butter, coconut oil, sugar, baking powder, baking soda, and salt in the bowl of a stand mixer. Fit the mixer with the paddle attachment. Set the mixer to low to moisten, then switch to medium speed and cream until light and fluffy, about 5 minutes, scraping as needed.
8 ounces unsalted butter, ⅔ cup virgin coconut oil, 2¼ cups granulated sugar, 2½ teaspoons baking powder, 1 teaspoon baking soda, ¾ teaspoon kosher salt
With the mixer running, add egg whites, one at a time.
1 cup egg whites
Add vanilla and almond extracts and mix 30 seconds.
2 tablespoons pure vanilla extract, 1 teaspoon almond extract
Scrape down the bowl and paddle.
Set mixer to low speed and slowly add one-third of the flour, followed by one-third of the buttermilk. Mix just until each addition is roughly incorporated. Add the remaining flour and milk, alternately, one-third of each at a time. Mix just until smooth.
2 cups cultured low-fat buttermilk
Turn off the mixer and use a rubber spatula to scrape all dry ingredients from the bottom. Mix on low speed just until dry ingredients are incorporated.
Divide batter evenly between the prepared cake pans and bake about 40 minutes or until the cakes internal temperature registers 210°F. The cakes should be pale, brown around the edges and firm. A toothpick inserted in the middle of each cake should come out almost clean – with just a few crumbs attached.
Transfer cakes to a wire rack and cool 15 minutes. Remove cakes from the pans and remove the parchment. Return them to the wire racks to cool completely.
If not serving the cake within a couple of hours, wrap the cake layers tightly with plastic wrap up to 24 hours ahead. Keep the frosting and filling refrigerated until ready to frost.