Step 1

Preheat oven to 180°C/160°C fan forced. Grease two 20cm square cake pans. Line the base and sides with baking paper. Sift flour, baking powder and salt into a bowl.

Step 2

Use a stand mixer with the paddle attachment or electric beaters to beat the butter and sugar in a large bowl until pale and fluffy. Add eggs, 1 at a time, beating well after each addition. Add vanilla and beat until combined. With the mixer on low speed, add flour mixture and buttermilk in alternating batches, beginning and ending with the flour, until just combined. Divide the cake mixture between the prepared pans and smooth the top. Bake for 40-45 minutes or until a skewer inserted into the centre of the cakes comes out clean. Set aside in the pans for 10 minutes to cool slightly before turning onto a wire rack to cool completely.

Step 3

Meanwhile, to make the buttercream, use a stand mixer with the whisk attachment or electric beaters on medium speed to beat the butter in a large bowl until pale and creamy. Gradually add cream cheese and whisk until smooth. Scrape the bottom and side of the bowl then add half the icing sugar and half the vanilla. Whisk on low speed until combined. Add the remaining icing sugar and vanilla. Whisk on low speed until combined. Increase speed to medium-high and whisk for 5 minutes or until fluffy. Add a little food colouring to tint the buttercream pale pink.

Step 4

Place 4 biscuits in a food processor and process until coarsely crushed. Transfer to a small bowl with 1 cupful of the buttercream and mix until well combined.

Step 5

Use a serrated bread knife to trim and level the top of each cake. Use a little plain buttercream to secure 1 cake layer, base-side down, onto a cake board or serving platter. Spread the crushed biscuit buttercream over the top of the cake. Place the remaining cake, base-side up, on top. Spread the plain buttercream over the top and sides of the whole cake. Use an offset palette knife or cake scraper to smooth the sides and top.

Step 6

Spoon plain buttercream into a disposable piping bag and snip a 1cm wide opening. Pipe peaks of buttercream on top of the cake and arrange 20 remaining biscuits on top, gently pressing to secure. Decorate sides of the cake with hundreds and thousands.