Mix the blueberries, icing sugar and lemon juice in a saucepan over a medium heat, and heat until the blueberries have burst and released their juices and the mixture has thickened. Set aside to cool slightly.
Combine the cream cheese, marshmallow fluff, milk and vanilla paste in a saucepan over a low heat and bring to just under boiling. Remove from the heat.
Swirl the blueberry jam through the warmed fondue mixture and sprinkle with the crushed ginger biscuits.
Serve in the pot at the table with strawberries andbrownies, or any other dippable treat you like!