Preheat oven to 325°F (160°C). Grease an 8" x 8" square, 9" round, or 11" x 7" baking pan.
Using an electric mixer on medium speed, beat the cream cheese, sugar, and flour until well-blended and smooth. Add the egg and vanilla, and mix until combined.
Spread the mixture evenly into the bottom of prepared pan. Bake 15 to 20 minutes, or just until set. Set the pan aside while you prepare the topping.
To make the topping:
Increase the oven temperature to 375°F (190°C).
Place the blueberries in a medium bowl. Add the granulated sugar and lemon juice, and toss to coat. Set aside.
In a separate bowl, mix the flour, brown sugar, and cinnamon. Add the butter and mix with a pastry blender or a fork until combined. The dough will be crumbly. Add the pecans, and toss to mix.
Spoon the blueberry mixture over the cream cheese layer.
Sprinkle the crumb mixture evenly over the blueberries.
Bake 22 to 25 minutes, or until the top is lightly browned and the blueberries are bubbly.