Vanilla Birthday Layer Cake

Method

1. Preheat oven to 170°C (150°C fan). Grease and line three 20cm round tins (you will bake in two batches if needed).
2. Cream butter and sugar until very pale and fluffy — at least 5 minutes.
3. Add eggs one at a time, beating well. Fold in flour, baking powder, vanilla, and milk.
4. Divide into three tins. Bake for 25 to 30 minutes until a skewer comes out clean. Cool completely.
5. For the buttercream: whisk egg whites and sugar in a heatproof bowl over simmering water until the sugar dissolves and mixture reaches 70°C.
6. Transfer to a stand mixer and whip on high until stiff, glossy, and completely cool (about 10 minutes).
7. With the mixer on medium, add butter one cube at a time. It may look curdled — keep mixing. It will come together into smooth, silky buttercream.
8. Add vanilla and salt. Whip for 2 more minutes.
9. Level each cake layer. Split each horizontally to make 6 thin layers. Stack with buttercream between each layer.
10. Apply a crumb coat, chill for 30 minutes, then apply the final coat. Decorate with sprinkles and candles.