Pre-heat your oven to 160C Fan/350F/Gas Mark 4, and grease and line a 12" x 9" traybake tin
Make the cake by mixing the baking spread (or butter) and caster sugar in a large mixing bowl until fluffy, about 2-3 minutes, ideally using an electric mixer
Add the eggs, vanilla extract and milk, and mix until fully incorporated
Use a spoonful of the self raising flour to coat the raspberries lightly. Then gently whisk or fold into the batter the remaining self raising flour. Add the raspberry and flour mix, and the white chocolate chips, and fold them in gently with a silicone spatula or wooden spoon
Pour the mixture into the tin, spread it out into an even layer
Bake for 25-30 minutes or until a skewer inserted in the centre comes out clean. Leave to cool fully either in the tin or on a cooling rack
Make the buttercream by mixing the butter in an electric mixer with the paddle attachment for a few minutes. Add the icing sugar and milk and mix to combine, then add the melted white chocolate and mix until smooth. You can add more milk if the buttercream is too stiff
Spread or pipe the buttercream all over the cake, and decorate with the fresh raspberries, white chocolate chips and freeze dried raspberries
To serve, slice into squares. Store any leftovers in an airtight container in a cool place and eat within 3 days
Notes
Make sure all your ingredients (particularly the butter and eggs) are at room temperature before you start baking.
I used a baking spread for the cake and unsalted butter for the buttercream.
It is best to use fresh raspberries for this cake, frozen ones can release too much moisture and make the cake soggy.
You will need a 12" x 9" traybake tin for this recipe. However, if you want to make it in a 9" square tin, check the recipe notes for the measurement details.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50).
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.
If you want to make this cake in a 9" square tin you will need: