1. Preheat oven to 350 degrees.
2. Prepare the cake pans with baking spray and line with parchment paper rounds.
3. Combine eggs, 1/4 cup milk and vanilla in a small bowl with whisk by hand until lightly combined.
4. On low speed in a stand mixer, combine dry ingredients.
5. Add butter and remaining 3/4 cup milk on low speed and mix until combined.
6. Increase speed to medium and beat for 2 minutes, until light and fluffy. Scrape bowl with a rubber spatula.
7. Add egg mixture in three parts, mixing on medium speed for 30 seconds after each addition. Scrape down the sides of the bowl.
8. Pour batter evenly into the two prepared cake pans, scraping bowl with a rubber spatula. Spread batter with an offset spatula so that it is evenly in pan.
9. Bake at 350 degrees for 25-30 minutes, or until a wooden toothpick inserted in the center of the cake comes out clean and the cake springs back when pressed lightly in the center. The cake will slightly shrink away from the sides of the pans.
10. Let the cakes cool in the pans on a wire rack for 10-15 minutes. Run a small offset spatula around the outside of the cake to loosen from the pan, then carefully flip the cake out of the pan onto the wire rack. Place the cake right side up on rack and let it cool completely before icing.
11. Assemble cake by spreading a layer of Duff’s buttercream using an offset spatula onto one cake layer. Place the second cake layer on top of the buttercream-covered first.
12. Ice the entire assembled cake with Duff’s buttercream.