- Preheat oven to 350°F and butter the bottom and sides of a 9" x 9" cake pan.
- Cream butter and sugar with an electric mixer until light and fluffy. Beat in egg. Stir in milk and vanilla until blended.
- In a small bowl combine flour, salt and baking powder, and with a few swift strokes mix this into the butter and egg mixture. Gently fold in blueberries. Spoon into the prepared pan.
- In a small bowl, lightly mix the topping ingredients with a fork until crumbly. Sprinkle over the cake batter.
- Bake 50 minutes. Cool on rack and cut into squares to serve.
Recipe from Gathering Around The Grill Cookbook