In a large bowl, cream butter and sugar until light and fluffy. Beat in eggs and vanilla until blended. Combine the flour, baking powder and salt, then add to creamed mixture alternately with milk, beating well after each addition. Fold in blueberries. If using frozen blueberries, use without thawing to avoid discolouring the batter.
Pour into a greased 13-in. x 9-in. baking dish. For topping, combine sugar and cinnamon. Cut in butter until mixture resembles coarse crumbs. Sprinkle over batter.
Bake at 375F for 35-40 minutes or until a toothpick inserted near the centre comes out clean. Cool on a wire rack. Yield: 12-16 servings.
Nutritional Information Per Serving (1 piece): 344 calories 11 g fat 55 mg cholesterol 414 mg sodium 57 g carbohydrate 1 g fibre 5 g protein