Preheat the oven to 350 degrees.

Line an 8 x 8 baking dish with foil or parchment paper.

In a medium bowl combine the flour, powdered sugar, and butter. Press this mixture into the bottom of the prepared pan and bake for 15 minutes.

Meanwhile, toss the peaches in a medium bowl with the sugar, lemon juice, cornstarch, and cinnamon. Set aside.

In a medium bowl combine all the ingredients for the crumble. Mix until the mixture is a sand like consistency.

Once the shortbread is removed from the oven pour the peach filling over top of the crust.

Sprinkle the crumble over top of the filling.

Bake for 35-40 minutes.

Remove from oven and cool completely.

Remove the bars from the pan using the foil or parchment and cut into bars.