Preheat oven to 350 degrees F. Line an 8x8 baking pan with foil, leaving an overhang on the sides for easy removal. Coat the foil lined pan in cookng spray.
For the crust/streusel: In a large bowl, stir together the flour, oats, brown sugar, and cinnamon. Cut in the cold butter using a pastry blender or two forks until the mixture turns into coarse, pea-sized crumbs.
Remove 3/4 cup of the mixture, put in a small bowl and mix in the almonds. Set aside the almond mixture, this will be the topping on the bars.
Evenly press the remaining oat mixture into the bottom of the baking pan. Bake for 15 minutes ; prepare the peach filling while the crust bakes.
For the filling: Whisk the egg and sugar together until smooth and creamy. Stir in the vanilla. Add the flour and salt. Whisk until combined. Gently fold in the peaches.
After the crust has cooked for 15 minutes, remove it from the oven and pour the filling over the hot crust. Sprinkle with reserved oatmeal and almond mixture. Bake for about 30 minutes or until golden brown on top. Place the pan on a cooling rack and cool for 30 minutes.
For the vanilla glaze: Combine the powdered sugar, milk and vanilla extract in a bowl; stir until completely smooth. Drizzle the glaze over the whole pan of bars.
Place the pan in the refrigerator and allow to chill for 2 hours before cutting into squares. The squares will keep for 3 days in the refrigerator.