Line a standard loaf pan with 2 layers of plastic, ensuring the base and sides are well-covered.
Place the blueberries and sugar in a small saucepan and bring to a simmer. Cook, mashing the blueberries with the back of a wooden spoon until the sauce is thick and glossy. Approximately 5-7 minutes.
In a large mixing bowl, whip the cream/cottage cheese, mascarpone and condensed milk together until thick and smooth. Add the lemon juice and continue whipping until well-combined.
To assemble the icebox cake, begin by adding a layer of the cream mixture then dollop on a few spoonfuls of blueberry mixture. Swirl the two together lightly with the back of a knife.
Add a layer of cookies. Continue layering, finishing with a layer of cookies as this will be the base once the icebox cake is served.
Cover tightly with plastic wrap and place in the fridge for at least 4 hours but ideally overnight.
Remove from the fridge once you are ready to serve. Uncover then invert onto a serving platter. Gently remove the loaf pan and the plastic. Cover with blueberries and serve in slices.