To a bowl, combine the butter, sugars, egg and beat until creamed and well combined, about 3 minutes. Add the flour, cornstarch, baking soda, salt and beat until combined. Add chocolate and almonds.
Using a cookie scoop, or your hands, form approximately 20 equalized mounds of dough. Place mounds on a large plate, cover with plasticwrap and refrigerate for at least 2 hours.
Preheat the oven to 175°C, line a Silpat. Place dough mound on Silpat, spaced at least 2 cms apart and bake for about 10 to 11 minutes. Don't overbake, cookies will to firm up as they cool.