Combine the flour, baking soda, baking powder, and cornstarch in a large bowl and mix with a spoon. Set aside.
In another mixing bowl, cream together the butter with the brown and white sugar using a hand held mixer or stand mixer until nice and fluffy about 2 minutes.
Add in the egg and egg yolk, vanilla extract, and almond extract and beat to combine, scraping the bowl down as necessary with a rubber spatula.
Add the dry ingredients into the wet ingredients in two batches. Mix in with a wooden spoon or rubber spatula spoon.
Cover the dough with plastic wrap and place in the fridge for at least 1 ½ hours to chill. See notes
Preheat oven to 350F when dough is almost fully chilled.
To make uniform size cookies use a cookie scoop to scoop out equal portions of dough approximately 45g in weight. Gently roll the dough in your hands to form a tall ball (taller than it is wider) and place on a parchment lined baking sheet (or line with a sil pat). Leave enough room for the cookies to spread and not spread into each other – about 3 inches apart.
For a thinner style cookie bake in a 350F oven for 15 minutes. The edges should be golden brown. Then continue on from step 10.
For a thicker style cookie bake in a 350F oven for 11 minutes. Remove the pan from the oven and use the back of a spoon to gently nudge the edges of the cookies back towards the middle. This will counteract the spreading of the cookie and build up the volume in the middle. It also adds a bit of ridges which gives the cookies an appealing texture. Place the pan back in the oven as quickly as possible and continue to cook for another 5-8 minutes, until the cookies are golden brown on the edges.
Remove from the oven and if you want you can use a spoon to gently push the edges of the cookies towards their centers, so they aren’t as spread out. This is up to your personal preference (thinner vs thicker cookie).
At this point you can also sprinkle on any toppings to any of the cookies that you would like. See notes. After adding these ingredients to the tops, I press them down a bit into the still-soft dough so they get sort of glued into place as the cookie cools. The heat of the cookie will be enough to turn chocolate chips melty.
If you are baking for someone with nut allergies, bake all the nut free cookies first, and put them in a safe contamination-free place, then bake the cookies that will have nuts added to the tops.
Cookies are best served warm, so dig in and enjoy!