Preheat the oven to 350°F(177°C). Line baking sheet with parchment paper or silicone baking mat. Set aside.
Mix the flour, powdered sugar and cornstarch in a medium bowl.
Beat the butter almost 1-2 minutes until creamy with a hand-held mixer or with paddle attachment if using a stand-mixer.
Add the vanilla and stir.
Add in the dry ingredients in 2 bacthes at low speed. When the dough looks crumbly, stir at medium-high speed for almost 15 seconds until the dough comes together.
Make 2 teaspoon (17 grams) big balls. You can take the dough with a cookie scoop, place on a baking sheet and then roll each dough into balls.
Flatten the dough with your palm or fingers. Press the dough with the tines of a fork to give their shape.
Bake for 16-18 minutes until the top of the cookies set. The cookies shouldn't be brown. When you try to hold the cookies, they shouldn't fall apart.
Keep the cookies on baking sheet for almost 10 minutes before transferring them to a wire rack to cool completely.
Once cooled, you can coat the cookies with powdered sugar. You can place the cookies one by one in a bowl that is full of powdered sugar and cover them with sugar. Remove the excess by shaking the cookies before placing on a plate.