1. Preheat your oven to 180°C/Fan 160°C/Gas 4. Line a 12-hole muffin tin with paper cake cases. Melt the butter in the microwave or in a pan on the hob, then set aside to cool for a few mins.
2. Tip the sugar into a mixing bowl. Sift in the flour and baking powder. Add a small pinch of salt and whisk everything together to mix.
3. In a separate bowl or jug, beat the melted butter with the eggs, soured cream and strawberry compote. Ppour the wet ingredients into the dry ingredients and fold them together with a flexible spatula till they're evenly combined. Add 1-2 heaped tbsp batter to each cake case, dividing the mix evenly between the cases.
4. Slide the cupcakes into the oven and bake for 25-30 mins till they're golden and firm to the touch. Let the cupcakes cool in the tins for a few mins, then transfer them to a wire rack and let them cool completely.
5. To make the frosting, pop 150g white chocolate buttons in a heatproof bowl with the butter and microwave till melted, checking every 10 secs. If you don't have a microwave, set the bowl over a pan of simmering water, making sure the water isn't touching bowl, and let the chocolate melt. Let the chocolate cool for 2-3 mins.
6. Stir the vanilla extract and sour cream into the melted chocolate. Sift the icing sugar into a seperate bowl, then add around a quarter of the icing sugar to the melted chocolate. Stir well to combine. Repeat, till you have added all the icing sugar. Chill for 30 mins-1 hr till the icing has thickened.
7. Pipe or spoon the icing on top of each cupcake. Top each cupcake with a strawberry half or quarter, a chocolate button and a little edible glitter, if liked. Serve straight away.
8. Eat Me, Keep Me
These cupcakes will keep in the fridge for 2-3 days, but only add the strawberry decoration just before serving – this stops the strawberry juices bleeding into the icing and staining it.
9. You're The Tops
The icing is rich and indulgent. If you'd prefer somehting lighter (and faster), soft whip a pot of double cream and stir in 1 tbsp icing sugar then use that to top the strawberry sponges. Decorate with the strawberries and chocolate buttons, if liked.