To make the vanilla traybake:
Preheat the oven to 170 C / Gas 3.
In a bowl, combine the caster sugar, self-raising flour, baking powder and oil, mix until the consistency is smooth and then mix in the milk, eggs and vanilla extract.
Line and grease a 20 x 30cm tray bake tin and pour the cake batter in. Tap the sides and base of the tin to remove bubbles.
Bake on the middle shelf of the oven for 30 minutes or until risen, golden and cooked the whole way through.
If your traybake looks slightly domed when you remove it from the oven, wait for it to cool a little and when you remove it from the tin rest it face down- as the cake continues to cool it should become a little more evenly shaped and easier to work with.
To make the buttercream icing:
Mix the softened butter, vanilla extract, icing sugar and water together until you have a smooth buttercream icing. Keep this to one side until you're ready to assemble the cakes.
To prepare the fondant icing:
Break off 2/3 of the block of white ready to roll icing and work in your hands until it's warm and pliable. Add a little of the blue icing colour tint at a time, working through the icing until you've achieved the shade you want evenly throughout.
Split the remaining chunk of white icing into two pieces and colour one of these pieces with the red icing tint until you have achieved an even shade that complements the blue icing you've prepared. You now have red, white and blue fondant icing to work with.
To assemble the fondant fancies:
Cut the tray bake into squares approximately 5cm x 5cm - I've provided measurements and instructions to ice six of these, if you're making more just scale up the ingredients.
Spoon a small spoonful of buttercream icing on to each cake cube and spread evenly across the top.
Pull off a small chunk of the blue fondant icing (just enough to ice one cake) and work in your hands until it's warm and easy to manipulate.
Dust a clean surface with some icing sugar and roll out the icing until it's approximately 2 mm thick and with a large enough surface area to cover an entire cake cube.
Carefully lift up the icing and lay it over the top of one of the cake cubes, work the icing carefully smoothing it out over the sides without overlapping. Then trim off the excess icing and smooth the edges.
To make the Union Jack design, roll out the white icing until it's approximately 2mm thick. For the main white cross cut one length of icing 15mm wide and 150mm long. Lay this across the centre of the top of the iced cake and glue down with a few dots of writing icing. Trim excess icing from the sides of the cake.
Then cut two lengths approximately 15mm x 70mm, arrange into a cross and glue on to the top of the fondant fancy.
Then cut four lengths approximately 12mm x 80mm, finish one end of each length with a diagonal edge and glue down with writing icing as follows.
Then roll out the red icing until it's approximately 2mm thick. Cut two lengths 10mm x 150mm, lay these over the top of the white cross so that there is a small white boarder either side.
Then cut four pieces of red icing approximately 3mm x 60mm, finish one end of each length with a diagonal edge and arrange over the top of the diagonal white panels, trim away any excess icing. Repeat this icing process with each cake.
Give yourself plenty of time with this recipe and don't rush the icing. These little cakes look great with a band of royal gold ribbon wrapped around the base.