Begin by preheating the oven to 170° Celsius. Grease the base and sides of four 6-inch round cake tins, then line the bottoms with parchment paper. If you only have two cake tins available, bake the cakes in two batches, allowing the tins to cool before reusing them.

In the bowl of a stand mixer, combine the room-temperature butter and caster sugar. Beat the mixture for approximately 5 minutes, or until it becomes noticeably pale, light, and fluffy. This step helps create a tender and delicate cake texture.

In a separate bowl, sift together the plain flour, baking powder, and salt. Set the dry ingredients aside while you prepare the wet mixture.

Add the eggs one at a time to the creamed butter and sugar, beating thoroughly after each addition. Add the vanilla extract and continue mixing until everything is evenly incorporated.

With the mixer running on low speed, gradually add the flour mixture and buttermilk alternately. Start and finish with the dry ingredients, mixing only until the batter comes together. Avoid overmixing, as this can result in a denser sponge.

Divide the batter evenly among the prepared cake tins. A measuring cup and kitchen scale can make this easier and help ensure that all four layers bake to a similar size and thickness.

Bake for 20–25 minutes, or until a toothpick inserted into the center of each cake comes out clean. Allow the cakes to rest in their tins for about 10 minutes before carefully turning them out onto a wire rack. Remove the parchment paper and leave the cakes to cool completely.

Once cooled, wrap each sponge securely in cling film and refrigerate for 1–3 hours. Chilling the cakes makes them firmer and easier to stack and decorate without excessive crumbs.

Place the water and caster sugar in a small saucepan over low heat. Stir gently until the sugar has completely dissolved.

Increase the heat to medium and bring the syrup to a boil, stirring regularly to ensure the mixture remains smooth. Remove the saucepan from the heat and stir in the vanilla extract.

Set the syrup aside and allow it to cool completely before brushing it over the cake layers.

Place the softened butter and vegetable shortening in the bowl of a stand mixer. Beat for around 5 minutes, or until the mixture is smooth, creamy, and noticeably lighter in texture.

Gradually add the sifted icing sugar, approximately one cup at a time, beating well after each addition. As the buttercream becomes thicker, slowly pour in the whipping or heavy cream. Continue beating until the frosting becomes light, smooth, and fluffy.

Add the vanilla extract and mix once more until the flavor is evenly distributed throughout the buttercream.

Place the first layer of chilled sponge onto a thin cake board that is the same size as the cake, keeping the flat side facing downward. Using a pastry brush, lightly coat the surface with the cooled vanilla syrup. Repeat the syrup application for each remaining cake layer as you assemble the cake.

Fit a piping bag with a ½-inch round nozzle and fill it with the vanilla buttercream. Pipe a ring of buttercream around the outer edge of the first cake layer. This creates a neat frosting dam that helps contain the filling and keeps it from spilling over the sides.

Fill the center of the buttercream dam with additional frosting, then gently smooth the filling with an offset spatula. Alternatively, pipe the buttercream directly over the entire surface and smooth it evenly if preferred.

Place the next cake layer on top and repeat the process with the vanilla syrup, buttercream dam, and filling. Continue until all four layers of vanilla buttermilk cake have been stacked.

Refrigerate the assembled cake for at least 1 hour to allow the buttercream to firm up. Once thoroughly chilled, use a sharp knife to carefully trim away any excess buttercream that has bulged around the sides. The goal is to create the characteristic rustic, semi-exposed appearance of a naked cake while keeping the layers neat and defined.

When the cake is chilled and neatly trimmed, it is ready for its floral decoration. Prepare the roses by trimming their stems to approximately 2 inches in length.

If the flowers are not organic or specifically grown for culinary use, do not insert the stems directly into the cake. Wrap the stems securely with floral tape to create a protective barrier. Another option is to roll a small amount of sugar paste or fondant into a ball and use it as a barrier between the flowers and the cake.

Plastic straws can also provide an effective protective method. Insert the straws into the cake where you want to position the flowers, then place the prepared flower stems inside the straws. Arrange the roses carefully across the top of the cake to create an elegant, natural-looking floral finish.

Once decorated, the Floral Naked Vanilla Cake is ready to serve.