Preheat oven to 375 degrees. Spray or butter a cake pan about 12" x 8".
In a medium bowl, cream together the shortening and sugar. Add egg and milk.
In a separate bowl, sift flour and baking powder together. Add dry ingredients to bowl with wet ingredients. Mix to combine.
In a separate bowl dust blueberries with about 2 tablespoons of flour. This prevents the blueberries from sinking to the bottom. Discard any extra flour that doesn't stick to the blueberries. Add floured blueberries to the cake batter and fold in gently to combine.
Pour batter into prepared pan and bake for about 25 minutes. Let cool before slicing into squares. Serve with butter. Enjoy!