Preheat the oven to 350 degrees. Spray an 8 x 8 baking dish with cooking spray.
In a large bowl combine the flour, sugar, baking powder, and cinnamon. Mix well.
Add in the egg, milk, butter, and lemon zest. Mix until the dry ingredients are just moistened. Use your hands if needed as the batter is very thick.
Gently fold in the blueberries then spread into the prepared pan.
For the topping combine the sugar, flour, pecans, and cinnamon in a bowl. Add in the butter and use your hands to mix until the mixture becomes coarse. Sprinkle over top of the batter.
Bake for 45 minutes then cool completely on a wire rack.
To make the glaze whisk together the milk and powdered sugar. Drizzle over top of the cooled cake.