Put the pitted mirabelle plums in a large saucepan and cook over high heat. Stir regularly. The fruits release liquid quickly and soften quickly. Then puree the fruit (we like a very fine, creamy jam without large pieces of fruit, but you can do that as you wish).
Add the preserving sugar and bring to the boil. Keep stirring continuously. Let the jam simmer for about 3-4 minutes.
Finally add the prosecco. Stir briefly and immediately pour into the prepared glasses.
The Prosecco gives you a fruity jam with a slightly fresh note.