Preheat your oven to 350°F (175°C). Grease a loaf pan and line it with parchment paper if desired.
In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
In a large bowl, whisk the eggs, granulated sugar, and brown sugar until smooth and slightly pale. Add milk, oil, and vanilla. Stir until combined.
Gently fold the dry ingredients into the wet ingredients just until no dry streaks remain. Do not overmix.
Toss blueberries with 1 tablespoon flour to prevent sinking. Fold them gently into the batter.
In another bowl, beat cream cheese, sugar, egg, and vanilla until smooth and creamy.
Pour half the bread batter into the prepared pan. Spoon the cream cheese mixture evenly over the batter. Top with remaining batter.
Use a knife to gently swirl if desired, or leave it layered.
Bake for 50–60 minutes, tenting loosely with foil after 40 minutes if the top browns too quickly.
Let cool in the pan for 15 minutes, then transfer to a rack to cool completely before slicing.