VANILLA CAKE

1. Preheat oven to 350f/180c. Grease and flour two 8 inch cake tins. 
2. In a large bowl, sift together the cake flour, baking powder and salt. In a second bowl, combine the cream, yoghurt and vanilla paste. 
3. In the bowl of a stand mixer fitted with the paddle attachment (if you have the attachment with the blade it is great for this) or using an electric hand mixer, beat the butter and sugar on high for 5 minutes until pale, light and fluffy. Add the eggs one at a time, scraping the bowl down well after each addition. 
4. Turn the mixer off, and add a third of the flour mixture. Mix until just combined, then add half of the yoghurt/cream mixture. Mix on low. Add the second third of the flour mixture, followed by the remaining liquid, and finishing with the rest of the flour. Mix on low until just incorporated. Take care not to overmix. 
5. Divide the batter evenly between the two cake pans. Bake for 30-35 minutes, or until a skewer comes out clean. 
6. Cool 30 minutes in the pan, then remove and allow to cool completely. 

SWISS MERINGUE BUTTERCREAM

1. In the bowl of stand mixer, combine egg whites, vanilla and sugar. Whisk briefly until combined. Place the bowl of the mixer over a small saucepan of water, taking care that the water does not touch the bowl. Turn the heat to medium. 
2. Whisking occasionally to prevent the egg white cooking, bring the egg mixture to 150f/65c. Place the bowl back onto the mixer, fitted with the whisk attachment, and whip on high speed until the mixture has doubled in volume and is completely cool. Feel the outside of the bowl with your hands - there should be no trace of heat left (this is especially important for the next step to ensure that the butter does not melt when you add it). Cooling may take up to 20 minutes. 
3. Once the bowl is cool, add the butter one chunk at a time. If the mixture looks curdled/melted, do not worry, just continue whipping, it will come together!

ASSEMBLY

1. Slice each cooled cake into two 1 inch layers (4 layers total) using a cake leveller, or a sharp bread knife. Trim the top of each cake if necessary to ensure a smooth level surface. If you are using a cake board, spread a small amount of the buttercream onto the board, before placing the first layer of the cake onto it. Place the board onto a turntable or lazy susan. 
2. Place ¾ cup of buttercream on top of the bottom layer. Smooth out with an offset spatula, and place the second layer of cake on top. Repeat until the cake is stacked. Crumb coat the entire cake with a thin layer of buttercream. Ensure that the top is smoothed off, as it will not get covered later. Place the cake in the fridge for 20-30 minutes to cool 
3. While the cake is cooling, colour the buttercream. Divide the remaining buttercream in two. Leave one half white. Set aside a small amount of the second half of buttercream, and colour this blue. Colour the remainder red. If you would like your colours to be slightly darker, add a small drop of black gel fool colouring. I omitted this step, as I wanted my colours to be quite pastel.
4. Prepare three large piping bags, one fitted with a coupler. (If you dont have a coupler, prepare four bags, you need both a star tip and a round tip for the white). Fill a star tipped bag with blue, a round tipped bag with red, and the bag with the coupler with white. 
5. Remove the cake from the fridge. Beginning with blue, pipe three alternating dots of blue and white stars down the side of the cake (they will not go the whole way down). Using an offset spatula or the back of a spoon, smear the dots, leaving a 'tail'. Wipe the spatula off on a damp towel in between each smear to avoid colour mixing. Pipe the second line of dots on the tail of the first, beginning with white. (so the blue dot has white piped on it, and so forth)  Continue piping until you have seven lines, consisting of three smeared dots each. 
6. Swap the star tip for a round tip on the white piping bag. Starting beneath the first line of stars, and beginning with red, pipe three alternating blobs of white and red buttercream down the cake. Repeat the smearing process, remembering to wipe the spatula between. Continue lines of three dots until you are in line with the end of the 'star' section. 
7. Extend the lines of red and white 'stripe' dots up the cake. I had six dots in each row. Continue to repeat the piping and smearing process, until you are approximately half way around the cake. At this point you can choose to add another 'star' section, or just continue around the  cake with white and red stripes. When you reach the end, finish off the lines of stripes with a single blob of buttercream.