Preheat the oven to 350 degrees Fahrenheit. Lightly spray a 13 x 9 x 2-inch baking dish with cooking spray. Or you can line it with aluminum foil and spray it with cooking spray for easy removal.
In a medium mixing bowl, whisk together the 2 cups cake flour and 4 tablespoons cornstarch, and set aside.
Using a hand mixer, cream together 1 cup butter, ½ cup granulated sugar, and ½ cup brown sugarr. Add the beaten 1 egg yolk,1 teaspoon vanilla, and the cake flour cornstarch. Mix until incorporated.
Pat the dough into the bottom of the prepared pan. Bake for 15-20 minutes until the edges are lightly brown. Let cool slightly.
In a microwave-safe dish or using a double boiler, melt the 12 ounces milk chocolate chips. I melted it in the microwave stirring 30 seconds at a time. Pour the chocolate on top of the cookie crust and spread evenly. Sprinkle the chopped 1 cup sliced almonds, on top.
Cut into small squares once cooled, and store in an airtight container.