Heat oven to 375 degrees. Spray a 9 x 13 baking dish with cooking spray or line with aluminum foil.

In medium bowl, mix together flour, sugar, baking powder, and salt.

Cut in the butter using two knives, a fork, or pastry blender until pieces are no bigger than the size of a pea.

Stir in the egg to create a crumbly dough.

Press half of the dough into an even layer in prepared pan.

In small bowl, toss strawberries with sugar and cornstarch. Spread strawberry mixture over crust in pan.

Mix oats, brown sugar and chopped walnuts with remaining dough. Crumble dough mixture over strawberry layer.

Bake for 40-45 minutes, or until lightly browned.

Let cool and cut into bars.