Bake chocolate muffins and let cool completely.
Meanwhile, prepare a custard and fill it into a piping bag with a serrated nozzle.
Sprinkle the cooled muffins thickly with pink sugar (e.g. “Flamingo Bussi “by ehrenwort.).
Cut a heart out of the center of the muffins with a very tall, heart-shaped cookie cutter – feel free to cut all the way through to the bottom – and use the leftover dough for other purposes. (Alternatively, use a sharp knife to cut out the heart-shaped hole).
Fill the heart-shaped hole with the custard and decorate all around the top with sugar pearl or sprinkles.
Chill cupcakes until ready to serve.