Preheat oven to 350 degrees F and grease two 9x5 loaf pans.

In a large bowl, cream together the butter, cream cheese, and sugar using a mixer until smooth.

Mix in the vanilla extract and add eggs one at a time.

Gradually stir in the flour, baking powder, and salt until just combined.

Carefully fold in the fresh blueberries by hand.

Pour the thick batter into the prepared pans evenly.

Bake for 50 minutes, or until a toothpick inserted in the center comes out clean.

Let cool slightly in the pan before removing and slicing.