Instructions

1. Preheat the oven to 350ºF. Cream butter with lemon and the sugar until light and fluffy.
2. Add the egg, banana and vanilla and beat until combined. Meanwhile, toss the blueberries with ¼ cup of flour ( this will keep them from sinking to the bottom) then mix in the remaining flour, baking powder and salt.
3. Alternate adding the flour and milk. Fold in the blueberries.
4. Prepare the topping. Place the butter, sugar and flour in a bowl and use 2 butter knifes to cut the butter until it's in small pieces. Add nuts and mix all together.
5. Grease a 9-inch square baking pan (or something similar) with butter or coat with non-stick spray. Spread batter into pan. Sprinkle batter with topping. Bake for 35 to 45 minutes. Check with a toothpick for doneness. If necessary, return pan to oven for a couple of more minutes.Let cool at least 15 minutes before serving.