Crush the cookies finely and mix them with melted butter.
Press the mixture into a springform pan lined with parchment paper and chill the base.
Melt the white chocolate over a double boiler and let it cool slightly.
Mix the sour cream with crème fraîche and vanilla extract until smooth.
Quickly stir the melted chocolate into the cream.
In a saucepan, cook about half of the blueberries with some sugar briefly until a compote forms. Let it cool.
Spread the cream over the cookie base and swirl in the blueberry compote with a spoon, creating a marble effect.
Sprinkle the remaining fresh blueberries on top and chill the cake for at least 4 hours, preferably overnight.
Garnish the cake with fresh blueberries before serving.
