Stone the mirabelle plums and place in a saucepan with 50 g of sugar. Stir in the sugar well and cook the mirabelle plums for about 10 minutes in a closed saucepan until soft (stir occasionally).
In the meantime, mix 20 g of vanilla pudding powder with 1 teaspoon of grated lemon zest and 40 g of sugar. Dissolve in 50 ml milk.
After 10 minutes, take the mirabelle plums off the stove and pound them well with a potato masher. Brush through a sieve until 400 ml of liquid is collected. Add the remaining 100 ml milk and stir in the vanilla pudding powder.
Put back on the stove and bring to the boil, let it boil briefly.