Step 1: Prepare the Pan

1. Preheat your oven to 350°F (175°C).
2. Grease a 9×5-inch loaf pan with nonstick spray or line it with parchment paper, leaving some overhang for easy removal.

Step 2: Mix the Dry Ingredients

1. In a large bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

Step 3: Cream the Butter and Sugar

1. In a separate mixing bowl, beat the softened butter and sugar with a hand or stand mixer on medium speed until light and fluffy, about 2-3 minutes.
2. Add the eggs one at a time, beating well after each addition.
3. Mix in the vanilla extract.

Step 4: Combine the Wet and Dry Ingredients

1. Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix just until combined—do not overmix.

Step 5: Fold in the Blueberries

1. Toss the blueberries with 1 tablespoon of flour to prevent them from sinking to the bottom of the loaf.
2. Gently fold the blueberries into the batter.

Step 6: Make the Cream Cheese Swirl

1. In a medium bowl, beat the softened cream cheese, sugar, egg, and vanilla extract until smooth and creamy.

Step 7: Layer the Batter and Cream Cheese

1. Pour half of the bread batter into the prepared loaf pan and spread it evenly.
2. Spoon the cream cheese mixture over the batter, spreading it gently.
3. Add the remaining bread batter on top, smoothing it with a spatula.

Step 8: Bake the Bread

1. Sprinkle turbinado sugar on top, if desired, for a crunchy finish.
2. Bake in the preheated oven for 55-65 minutes, or until a toothpick inserted into the center comes out clean.
3. If the top browns too quickly, tent the loaf with aluminum foil after 30-40 minutes.

Step 9: Cool and Serve

1. Allow the bread to cool in the pan for 15 minutes, then transfer it to a wire rack to cool completely.
2. Slice and serve as is, or drizzle with a lemon glaze for extra flavor.