Preheat a fan-forced oven to 140°C / 275°F or a conventional oven to 160°C / 320°F. Spray one 10-inch (25cm) and two 6-inch (15cm) cake tins with oil spray and line the bottoms with baking paper. Set aside.
Add the flour, baking powder and salt to a large mixing bowl. Use a whisk to combine. Set aside.
Add the butter and sugar to a large mixing bowl and whip on high speed until light and fluffy. Add vanilla extract and the eggs one at a time, mixing and scraping the bowl down each time, until they’re all in there.
Add half of the dry ingredients in the bowl along with half the milk. Stir on low medium speed until well combined. Scrape down the bowl and add the remaining milk, dry ingredients, yogurt and oil. Stir on medium low speed until well combined. Distribute the batter evenly amongst the four baking tins, starting with the 10-inch baking tin first.
Bake for 50–60 minutes, or until a tooth pick inserted in the middle of the cake comes out clean. If the tooth pick is coated with wet batter, continue baking for 10 minutes at a time until fully baked.
Allow the cakes to cool to room temperature in the tins, then chill them in the fridge overnight. Chilling your cakes overnight makes them easier to trim and decorate, so I always bake my cakes the day before I decorate them.
To trim your chilled cakes, use a cake leveller or large serrated knife to carefully trim the crust off the top of each cake.
To crumb coat your cake, add a dab of chocolate ganache onto a 10” cake board or flat serving plate. Use a small offset spatula to spread the frosting around before adding the first cake layer. Gently press down the center of the cake layer to make sure it’s stuck to the frosting underneath.