Preheat oven to 350°F (175°C) and grease and line an 8x8-inch baking pan with parchment
Beat cream cheese until smooth, add sugar, then beat in egg and vanilla until combined; set aside
Toss blueberries with flour and lemon zest to prevent sinking
Cream butter and sugar until light and fluffy, add eggs one at a time, then stir in vanilla and sour cream
Whisk flour, baking powder, baking soda, and salt separately, then fold into wet mixture until just combined
Combine flour, brown sugar, and cinnamon for crumb topping; cut in cold butter until crumbly and refrigerate
Spread half the batter into pan, gently layer cream cheese mixture on top
Sprinkle blueberries over cream cheese, spoon remaining batter on top
Evenly sprinkle crumb topping over the surface
Bake for 45–50 minutes until golden and center is set
Cool at least 20 minutes before slicing