Preheat Oven: Preheat oven to 350°F (175°C). Grease and flour an 8×8-inch baking pan.
Prepare Crumb Topping: In a small bowl, mix flour, brown sugar, and cinnamon. Cut in cold butter until mixture resembles coarse crumbs. Set aside.
Make Cake Batter: In a medium bowl, cream together softened butter, cream cheese, and sugar until smooth. Beat in eggs one at a time, then stir in vanilla extract. Mix in flour, baking powder, and salt until just combined. Gently fold in blueberries.
Assemble Cake: Pour batter into prepared pan and spread evenly. Sprinkle crumb topping over the cake.
Bake: Bake for 40–45 minutes, or until a toothpick inserted in the center comes out clean. Let cool completely before slicing.
Serving and Storage Tips
