Preheat the oven to 350°F.

Spray an 8-inch square baking dish with nonstick cooking spray.

Combine the softened butter, brown sugar, granulated sugar, and vanilla extract in a large bowl. Beat with a hand mixer until pale and fluffy.

Add the egg to the bowl and continue to beat on medium speed until light and fluffy.

Add the flour, corn starch, baking soda, and salt to the bowl. Beat the mixture on medium speed, scraping down the sides of the bowl with a rubber spatula as needed, until the ingredients are combined.

Scrape down the sides of the bowl with a spatula, and add the chocolate chips to the mixture. Fold the chocolate chips into the dough until they are evenly distributed.

Transfer the dough to the prepared baking dish and press it into an even layer.

Bake the blondies on middle rack of oven until a toothpick inserted in the center comes out clean, about 25 minutes.

Check to see that blondies are done. Remove from oven or add time as needed.

Allow the blondies to cool at room temperature for a least 15 minutes. Refrigerate for 30 minutes to an hour, then slice and serve.