Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine the softened butter and cream cheese with the sugar, and beat until light and fluffy.

Add the eggs one at a time, mixing well after each addition until fully incorporated.

In a separate bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually add to the creamed mixture, stirring until just combined.

Dust the blueberries with flour and gently fold them into the batter.

Divide the batter between prepared loaf pans and smooth the tops.

Bake for 50-60 minutes or until a toothpick comes out clean.

Cool in the pans for 10 minutes, then transfer to a wire rack.