Pre-heat your oven to 140C Fan/325F/Gas Mark 3 and line a cupcake tin with paper cases
To make the cupcakes, mix together the butter/baking spread and caster sugar until smooth and fluffy, ideally using an electric mixer this will take about 3 minutes
Add the eggs, milk and vanilla, and mix well with an electric mixer until well combined
Add the self raising flour and whisk in gently with a hand whisk, or fold in with a spatula
Divide the mixture between the cupcakes cases, and bake them for 25-30 minutes, or until then are lightly golden and a thin skewer or a cocktail stick inserted in the centre comes out clean. Put them on a cooling rack to cool completely
When the cupcakes are fully cooled, peel off the paper cases and use a knife to cut them in half horizontally
Whip up the double cream with the icing sugar and vanilla extract
Pipe blobs of whipped cream onto the bottom layer of cake, or spread it on with a spoon, then spoon jam over the cream
Press the top of the cake back on and dust with icing sugar
Serve immediately and store leftovers in the fridge. Eat within 2-3 days