Preheat the Oven
Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper for easy cleanup.
Mix Dry Ingredients
In a medium bowl, whisk together the flour, cornstarch, baking soda, and salt. Set aside.
Cream the Butter and Sugar
In a large mixing bowl, beat the softened butter and 1 1/4 cups of sugar together until light and fluffy. This should take about 2-3 minutes.
Add Wet Ingredients
Add the egg, egg yolk, vanilla extract, and almond extract (if using) to the butter mixture. Beat until the mixture is smooth and fully combined.
Combine Wet and Dry Ingredients
Gradually add the dry flour mixture to the wet ingredients in two parts. Mix on low speed until just combined.
Prepare for Rolling
Pour the remaining 1/3 cup of sugar onto a plate or shallow dish.
Shape the Cookies
Scoop about 1 tablespoon of dough and roll it into a ball. Roll each dough ball in the sugar and place them about 2 inches apart on the prepared baking sheets.
Bake the Cookies
Bake one tray at a time on the middle rack of the oven for 8-10 minutes, or until the tops of the cookies are just set and slightly cracked.
Cool the Cookies
Let the cookies cool on the baking sheet for at least 10 minutes before transferring them to a wire rack to cool completely.