Preheat the oven to 350 degrees. Line a 9x9 baking dish with a parchment paper “sling”. Spray with baking spray (Baker’s joy or generic version). Set it aside.
In a small mixing bowl, whisk together the flour, cornstarch, and baking powder. Set it aside.
Using a medium size mixing bowl and a handheld mixer on high speed, beat the softened butter for 1 minute.
Add the granulated sugar, vanilla, and almond extract, and continue beating for 1 to 1 ½ minutes, until fluffy.
Lower the mixer speed to low, and add the eggs 1 at a time, beating well after each egg.
Increase the mixer speed to medium-low. Add the flour mixture 1 cup at a time, beating well after each cup just until well incorporated.
Add in the sprinkles, and mix just until combined.
Evenly spread the cookie dough into the bottom of the prepared baking dish. Bake for 20 to 22 minutes until just golden, and a toothpick inserted comes away clean.
Allow the cookie bars to completely cool.