Step 1

Preheat oven to 350°F with racks in the middle-upper and middle-lower portions. Line two baking sheets with parchment paper.

Step 2

Combine flour, baking soda, salt, and cornstarch. Set aside.

Step 3

Using a hand mixer or stand mixer fitted with the paddle attachment, beat butter, brown sugar, and granulated sugar until combined (about a minute or two). Add egg and vanilla, beating until combined and scraping the sides and bottom of the bowl as needed. Beat in the flour mixture until fully combined. Add the white chocolate and cookie pieces, stirring by hand until combined. Place the dough into the refrigerator for 15 minutes.

Step 4

Scoop the dough into 3-tablespoon portions and form into mounds that are higher than wider.

Step 5

Bake*** for 9-11 minutes, until the edges are just beginning to get a bit of golden brown color and the centers are still underdone. The cookies should be so soft that if you tried to pick them up off the baking sheet they would fall apart. Place the baking sheets on cooling racks and cool completely, they will firm up as they cool. Lightly place a few additional white chocolate chips on top of the cookies, if desired. See recipe notes regarding optional step of shaping the cookies after baking.