Preheat oven to 350 degrees F. Grease and flour an 8 inch square dish (2 quarts).

In a bowl, whisk together the flour, sugar and salt. Sprinkle chunks of butter (or grate it) over the flour mixture, then use a pastry cutter or your fingers to mix until evenly crumbly.

Measure out ¼ cup plus 2 tablespoons (6 tablespoons total) and set aside.

To the remaining flour mixture, add the baking powder and stir well. Add the egg yolk, milk and vanilla and stir until blended.

In a separate bowl, beat the egg white with a handheld mixer until stiff peaks form. Fold it into the batter (I was pretty rough with my folding technique and it still worked nicely).

Spread batter across the bottom of the dish. Toss the blueberries with the cinnamon and spread over the batter. Sprinkle reserved crumb mixture over the top.

Put the boy bait in the oven and bake for about 45 minutes or until top is golden brown.

Let the boy bait cool slightly, then serve warm. Alternatively, you can let it cool, then cut it and re-warm.