1-Combine 3 cups (375g) all-purpose flour, 3 cups (600g) granulated sugar, 2 1/2 teaspoons (10g) baking powder, and 1 teaspoon (6g) fine salt in a mixer bowl.

2-Slowly mix in 1 cup (226g) room temperature unsalted butter until the mixture looks like moist sand.

3-Add 1 cup (240g) egg whites slowly and mix on low speed until just combined.

4-Pour in 1 1/2 cups (360g) buttermilk in two parts, mixing on low each time.

5-Add 2 tablespoons (30g) vegetable or canola oil and 2 teaspoons (8g) vanilla extract; mix on low until fully incorporated. If using, add gel food coloring here.

6-Scrape the bowl sides and beat on medium speed for about one minute to lighten the texture.

7-Divide the batter evenly among the pans using a scale.

8-Bake for 33-35 minutes or until a toothpick comes out with a few moist crumbs.

9-Cool in pans for 10 minutes, then loosen edges and freeze pans for 30 minutes until layers cool completely.

10-Remove layers and level tops with a serrated knife before assembling, or freeze for later use and thaw for 20 minutes.

11-Beat 2 cups (452g) unsalted butter on medium speed for 30 seconds until smooth.

12-Add 1 tablespoon (12g) vanilla extract and 1/2 teaspoon (3g) fine salt; mix on low.

13-Gradually add 7 cups (907g) powdered sugar on low speed, adding 1/4 cup (60g) heavy whipping cream halfway through.

14-Scrape sides and bottom of the bowl frequently.

15-Continue mixing until you reach the desired consistency, adjusting with more cream or sugar as needed.

16-Add gel food coloring if desired and mix until uniform.

17-Place the first cake layer on a board and secure with a bit of frosting. Spread an even layer of buttercream on top, then repeat for each layer. Apply a thin crumb coat and chill for 30 minutes in the fridge or 10 minutes in the freezer. Finish with a thicker frosting layer and smooth it out. Decorate as you like for a personal touch.