Start by mixing your active sourdough starter with warm water in a large bowl. Stir well until the liquid looks smooth and the starter has fully mixed in. Slowly add the flour, sugar, salt, and melted butter. Use your hands or a wooden spoon to bring the dough together. It will feel sticky at first but this is normal. Continue mixing until you have a soft dough that holds together.

Turn the dough onto a clean counter and knead it gently for about ten minutes. The dough will become smoother and more elastic as you work with it. Place the dough back in the bowl and cover it with a clean cloth. Let it rest for about three to four hours or until it doubles in size. The rising time may vary depending on the temperature of your kitchen.

While the dough rises, prepare the cream cheese filling. In a small bowl, mix the cream cheese, sugar, and vanilla extract. Stir until it becomes smooth, creamy, and easy to spread. Set it aside.

Next, prepare the blueberry filling. In another bowl, mix the blueberries with flour and sugar. The flour helps the blueberries stay inside the loaf without making it too wet. Gently stir so the berries are coated well.

Once the dough has risen, gently punch it down to release the air. Place it on a flat surface and roll it out into a wide rectangle. The thickness should be even on all sides so the loaf bakes properly.

Spread the cream cheese mixture evenly across the rolled dough. Leave a small border on the edges so the filling does not spill out during rolling. Then sprinkle the blueberry mixture evenly on top of the cream cheese.

Carefully begin rolling the dough from one side to the other, almost like rolling a cinnamon roll log. Make sure the roll is tight but not squeezed too much. Seal the ends by pinching the dough lightly.

Place the rolled dough into a prepared loaf pan. Cover it again with a cloth and let it rest for about one to two hours. This second rise makes the loaf soft and gives it a fluffy texture.

Preheat your oven to a medium temperature of around three hundred and fifty degrees Fahrenheit. Once the loaf has risen again, sprinkle a small amount of sugar on top. This creates a pretty golden top with a gentle sweet crust.

Bake the loaf for about forty five to fifty minutes or until the top turns golden and the loaf sounds hollow when tapped. If the top becomes too dark too quickly, you can place a piece of foil lightly over it. Allow the loaf to cool before slicing so the fillings set properly.