In the bowl of your stand mixer, whip the eggs on high speed with the whip attachment until foamy.
Gradually add sugar (very slowly).
The eggs will take about 5 minutes to reach the ribbon stage. The ribbon stage is where the egg/sugar mixture is very light in color and very thick. When you lift your whip attachment, the batter runs back into the bowl and makes a ribbon effect before disappearing back into the mixture. You can also do a “figure 8″ pattern with the mixture, and if it stays visible for a few seconds before disappearing, you have reached the ribbon stage.
In the meantime you can heat the milk and butter together, just until the butter has melted. Remove from heat and then add the vanilla extract.
Sift flour, baking powder and salt in a separate bowl and set aside.
When you have reached the ribbon stage, turn your mixer to low and add in all of the dry ingredients at once.
Mix only until combined on low speed or you will deflate the batter.
Next, prepare a liaison with the milk/butter mixture. A liaison is a technique in which rather than pouring the liquids straight into the main batter, which will deflate, you will take out about 1 cup of the cake batter into a separate mixing bowl, and with a hand whisk, add the liquids to that batter. Whisk it all together and then proceed to add this liaison to the original cake batter in the KitchenAid bowl.
Fold gently to combine.
Pour into greased 8 inch pan.
Bake for 20 minutes, rotating pans halfway through, then lower the temperature to 325°F to continue baking until done (8 - 10 minutes).