Preheat the oven to 350 degrees F (175 degrees C).Coat the round cake pans with baking spray with flour and line the bottoms with parchment paper.Whisk together the flour, gelatin, baking powder, salt, and baking soda in a bowl.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter at medium speed until creamy, 2 to 3 minutes.
Gradually add the sugar, beating until light and fluffy, about 3 minutes.
Add the eggs, one at a time, beating on low speed and scraping down the sides of the bowl as needed, until just combined.
Add the flour mixture in three additions alternately with the buttermilk, beginning and ending with the flour mixture and beating on low speed just until combined after each addition.
Divide the batter evenly between the prepared pans.
Bake in the preheated oven until a wooden pick inserted in the center comes out clean, about 40 minutes.
Cool in pans on a wire rack for 10 minutes; remove the cakes from pans and cool completely on a wire rack, 1 to 1 1/2 hours.