Preheat oven to 180C/350F and line a 12 hole cupcake tray with cupcake liners.

Place butter/marg and sugar into a large bowl, or the bowl of your stand mixer and beat until light and fluffy, 2-3 minutes on medium-high speed.

Add in the eggs an vanilla, scraping down sides of bowl as necessary, and mix until well incorporated and smooth, about 1 minute on med-high speed.

Add in the flour, baking powder and salt, if using, and mix on low until it begins to come together.

Add in the milk and then mix on low-medium speed until well incorporated and smooth.

Fill each cupcake liner 3/4 full and then place in the oven for 18-22 minutes, until risen, lightly golden and an inserted skewer into the centre comes out clean.

Transfer to a wire rack immediately (I find if you leave the cupcakes in the pan, the liners peel away) and leave to cool.

Once cool, it's time to core the cupcakes! With a cupcake corer (I use the OXO Good Grips one) push into each cupcake, twisting as you go to remove the centre of the cupcake. Don't push it all the way down, you still want some cake at the bottom.

If you don't have a cupcake corer, use a small knife to cut a 1 inch wide circle out of the centre.

Don't throw away your cupcake cores, but cut them in half, so that you have a top to cover the filling.

Once all cupcakes are cored, place the jam into a heatproof bowl and microwave for 20 seconds. Using a teaspoon, divide the jam between each cupcake, leaving a little space at the top for you to put the cupcake tops back on.

Once all the cupcakes are filled and have their tops, place the white chocolate and butter into a heatproof bowl and microwave in 20 second increments, stirring in between, until melted and smooth. Leave to cool for 5 minutes, before spooning around 1tbsp onto each cupcake and smoothing with the back of your spoon until the cupcake is covered.

Place 3 fresh blueberries on top of your melted chocolate and leave to set.

Once set, cupcakes will keep in an airtight container, in the fridge for 3 days. Cupcakes are best served at room temperature.