Preheat the oven to 350°F and line a 9x5-inch loaf pan with parchment paper.
In a medium bowl, beat the cream cheese, sugar, egg, and vanilla extract until smooth.
In a large bowl, beat the butter and sugar together until light and fluffy.
Beat in the eggs one at a time, then add the vanilla extract and sour cream.
Whisk together the flour, baking powder, and salt. Gently mix into the batter, alternating with the milk.
Toss the blueberries with 1 tablespoon of flour.
Spread half the batter into the pan, add the cream cheese layer, then top with remaining batter and blueberries. Use a knife to gently swirl.
Bake for 60–70 minutes, until a toothpick comes out with a few moist crumbs.
Let the bread cool before slicing.