Cream the butter and sugar in a bowl with an electric mixer until pale and fluffy. Add vanilla extract, salt and the eggs one at a time, mixing with each addition. In a separate bowl, combine the flour and baking powder, then add to the batter in 2 additions, alternating with the milk. Add some white food colouring if you like, to lighten the colour of the batter and make it more wedding dress-like.

Grease a small aluminum bowl and 2 9-inch cake pans. They should reach the height of Barbie’s waist when stacked on top of each other. Evenly distribute the batter between the bowl and cake pans and bake at 350F for 35-60 minutes, until a skewer inserted into the middle of each cake comes out clean. The cake in the bowl will take longer to cook, since it’s a deeper pan. Allow the cakes to cool to the touch, then remove from the pans and cool completely.

Slice off the tops of the cakes to flatten the surface. Spread some buttercream between each layer and stack all layers, with the dome-shaped cake on the top. Trim the edges of the bottom 2 layers so that they extend downwards from the edges of the dome to look like a dress. Place the cake in the fridge until it firms up, 15-20 minutes.

Slice a small hole down through the center of the cake for Barbie to stand in. Undress Barbie and tie her hair in a bun, then wrap it in plastic wrap so that it doesn’t touch the buttercream. Wrap her legs in plastic wrap as well, then insert her into the cake. Move her arms upwards while you decorate the cake.

Cover the cake in a thin layer of buttercream and pop the cake in the fridge until it stiffens, about 10-15 minutes. Place the remaining buttercream in a piping bag fitted with a #126 piping tip. Pipe the top of the dress right onto Barbie and smooth the edges with a knife. Position the piping bag vertically against the base of the cake, with the widest part of the piping tip against the cake. Pipe straight up along the sides of the cake, gently wiggling the piping bag to create waves. Continue until the cake is fully covered.

Untie Barbie’s hair and move her arms downwards. Then slice and enjoy!