Step 1

Preheat oven to 350 degrees F. Line a large, rimmed baking sheet (12-inches by 17-inches or so) with parchment paper or foil and lightly grease with cooking spray (can also use a silicone baking liner; no need to grease).

Step 2

In a medium bowl, stir together the granulated sugar, brown sugar, baking soda and salt. Add the butter, egg and vanilla and mix until thick and well-combined. Add the flour and chocolate chips and mix until no dry streaks remain.

Step 3

Press the cookie dough onto the center of the prepared pan into an evenly thick 9-inch circle. When it bakes, it spreads to about 11-12 inches (the cookie will fit perfectly onto a 12-inch round cardboard circle you can find at most craft stores).

Step 4

If desired, top the cookie with additional chocolate chips or M&Ms. Bake for 13-16 minutes until the cookie is set around the edges and slightly crackly on top. Let the cookie cool completely on the baking pan – this helps the cookie set up so it can be easily lifted off the pan. Once cool, gently use the foil or parchment to lift the cookie off the pan; slide a thin spatula underneath to transfer. Cut into slices and serve!