Preheat oven to 375°F (190°C). Grease and flour a 9-inch square baking pan.
In a large bowl, whisk together 1.5 cups flour, baking powder, and salt.
In a separate bowl, cream together 0.75 cup sugar and shortening until light and fluffy. Beat in the egg, then gradually add the dry ingredients alternately with the milk, beginning and ending with the dry ingredients. Mix until just combined.
Gently fold in the blueberries.
Pour batter into the prepared pan.
In a small bowl, combine 0.5 cup flour, 0.33 cup sugar, and cinnamon. Cut in the cold butter until the mixture resembles coarse crumbs.
Sprinkle the crumb topping evenly over the batter.
Bake for 35-40 minutes, or until a wooden skewer inserted into the center comes out clean.
Let cool slightly before serving.
Notes
Serve warm with a scoop of vanilla ice cream or a dollop of whipped cream for an extra special treat.