Put the blueberries with the sugar, lemon juice in a pot and let simmer at low temperature for 5 minutes. Finally, finely puree with an immersion blender and let stand.
Whip the cream until stiff and leave in the fridge.
Finely chop the chocolate and melt over a water bath and set aside.
Melt the butter and let it stand so it cools down a bit.
Finely crush the cookies and mix with the butter.