Preheat oven to 175°C (350°F). Grease and line two 6-inch round cake pans.

In a medium bowl, whisk cake flour, baking powder, and bicarb soda.

In a large bowl, beat butter and sugar until light and fluffy.

Add eggs one at a time, mixing well after each.

Alternate adding dry ingredients and buttermilk into the butter mixture, beginning and ending with dry ingredients. Fold in lemon zest.

Divide batter evenly into pans, smooth tops, and bake for 25–30 minutes, or until a toothpick comes out clean. Cool 10 minutes, then transfer to wire racks to cool completely.

For the frosting, beat butter until creamy. Gradually add icing sugar, lemon juice, citric acid, and pink food coloring. Beat until smooth and fluffy.

Place one cake layer on a serving plate. Spread raspberry jam and a thin layer of frosting. Top with the second cake layer.

Apply a crumb coat of frosting and chill 15 minutes. Frost the cake fully with remaining frosting.

Garnish with crushed raspberries and lemon slices.