Pre-heat oven to 180 degrees c and line a muffin/cupcake tray with cupcake cases.
Put the butter, caster sugar, and vanilla extract in the bowl of your mixer and beat until pale and fluffy.
Add the eggs and mix to combine (don’t worry if it looks a little curdled at this stage, adding the flour will sort that out).
Add the flour and baking powder and beat again until combined.
Add the milk and beat again.
Divide the mixture evenly between your cupcake cases, bake for approximately 20 minutes, until a skewer comes out clean, and turn out on a wire rack to cool.
Once cupcakes have cooled, using an apple corer or knife, removed a section of cake from the centre, taking care not to go straight through to the cupcake case. Fill the space with raspberry jam and pop the piece of cake you removed back in.
To make the frosting:
Beat the butter and vanilla until pale and fluffy
Add the icing sugar and beat, slowly at first, until the mixture comes together. Add the custard powder and beat again to incorporate
At this point, you will probably find the frosting to be a little too thick. Add milk, one tablespoonful at a time, until it reaches your desired piping constituency.
Add the frosting to the cupcakes using either a piping nozzle of your choice or spread on with a palette knife.
Recipe Notes
I use a very heaped tbsp sized measuring spoon to measure the mixture into the cupcake cases. This will give around 16 cupcakes.
I find squeezy seedless jam ideal for these cupcakes.
I prefer about 4 very heaped tablespoons of custard powder in my frosting, as I like it to be quite custardy.
I like to use large nozzles, as they allow me to cover the cake quickly and easily (cake decorating is not a skill I possess!).