Heat Milk-Butter (Note 5): While egg is beating, place butter and milk in a heatproof jug and microwave 2 minutes on high to melt butter (or use stove).
Gently add flour: When the egg is whipped, scatter 1/3 flour across surface, then beat on Speed 1 for 5 seconds. Add half remaining flour, then mix on Speed 1 for 5 sec. Add remaining flour, then mix on Speed 1 for 5 – 10 sec until the flour is just mixed in. Once you can’t see flour, stop straight away.
Combine milk, vanilla & oil – Pour hot milk, vanilla and oil into the now empty flour bowl.
Lighten with some Egg Batter: Add about 1 1/2 cups (2 ladles or so) of the Egg Batter into the Milk-Butter (don’t need to be 100% accurate with amount). Use a whisk to mix until smooth – you can be vigorous here. Will look foamy.
Slowly add milk: Turn beater back on Speed 1 then pour the Milk mixture into the Egg Batter over 15 seconds, then turn beater off.
Scrape and final mix: Scrape down sides and base of bowl. Beat on Speed 1 for 10 seconds – batter should now be smooth and pourable.
Bake:
Pour batter into pans.
Knock out bubbles: Bang each cake pan on the counter 3 times to knock out big bubbles (Note 10 for why)
Bake 30 minutes or until golden and toothpick inserted into centre comes out clean.
Cool & frost:
Turn out & cool: Remove from oven. Cool in cake pans for 15 minutes, then gently turn out onto cooling racks. If using as layer cakes, cool upside down – slight dome will flatten perfectly. Level cake = neat layers.
Frost: Once cake layers are fully cool, top with frosting of choice, or cream and fresh berries or jam. See list of ideas in post!
Vanilla Buttercream:
Beat butter with paddle attachment in stand mixer for 3 minutes on high until it changes from yellow to almost white, and it becomes fluffy and creamy.
Add icing sugar / powdered sugar gradually in 3 lots, beating slowly (to avoid a powder storm) then once mostly incorporated, beat on high for a full 3 minutes until fluffy.
Add vanilla and milk, then beat for a further 30 seconds. Use milk only if needed to make it lovely and soft but still holds it’s form (eg for piping). Use immediately. (If you make ahead, refrigerate then beat to re-fluff).
