**Preheat the oven**
Preheat your oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment paper, leaving overhang on the sides for easy removal.
**Prepare the cream cheese layer**
In a mixing bowl, beat together the cream cheese, sugar, egg, and vanilla extract until smooth and creamy. Set aside.
**Mix the dry ingredients**
In a large mixing bowl, whisk together the flour, baking powder, baking soda, and salt.
**Cream the butter and sugar**
In another bowl, beat the softened butter and sugar until light and fluffy. Add the eggs, one at a time, followed by the vanilla extract and sour cream. Mix until smooth.
**Combine the wet and dry ingredients**
Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Gently fold in the blueberries and lemon zest.
**Assemble the bread**
Pour half of the bread batter into the prepared loaf pan. Spread the cream cheese mixture evenly over the batter. Add the remaining bread batter on top and smooth the surface.
**Bake**
Bake in the preheated oven for 50–60 minutes, or until a toothpick inserted into the center comes out clean. If the top browns too quickly, tent with aluminum foil during the last 15 minutes of baking.
**Cool and serve**
Allow the bread to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slice and enjoy!