Vanilla cake with vanilla buttercream

Preheat oven to 180°C. Grease three 20cm cake pans with extra butter, then dust with extra flour, shaking out excess.

Sift flour, cornflour, baking powder and salt into a medium bowl. Whisk sour cream, milk and vanilla in another bowl until combined.

Beat butter and sugar with an electric mixer on medium speed for 5 minutes or until pale and fluffy. Add eggs, one at a time, beating after each addition only until just combined. Beat in the flour mixture in three batches, alternating with two batches of the sour cream mixture until smooth and just combined. Divide cake mixture evenly among the pans.

Bake cakes for 25 minutes, rotating pans halfway through, or until a skewer inserted into the centre comes out clean. Leave cakes in pans for 10 minutes, before turning, top-side up, onto wire racks to cook.

Meanwhile, make the vanilla buttercream: Beat butter and vanilla with electric mixer until fluffy. Add half each of the sifted icing sugar and milk; beat on medium speed until combined. Add remaining sifted icing sugar and milk; beat for 5 minutes or until mixture is smooth.

To assemble cake, place one cake layer on a serving plate. Using a spatula, spread a quarter of the buttercream over the top. Repeat with another cake layer and quarter of buttercream. Top with final cake layer, then spread remaining buttercream generously over the top and side of the cake.