1 tsp. baking soda
1-1/2 tsp. cornstarch
1/2 tsp. salt
3/4 cup butter, melted (1 & 1/2 sticks)
3/4 cup light brown sugar
1/2 cup sugar
1 large egg + 1 egg yolk, room temperature
2 tsp. vanilla extract
1 cup chocolate chunks or chocolate chips
1. In a large bowl stir together the flour, baking soda, cornstarch, and salt. Set aside.
2. In a medium bowl, whisk the melted butter, brown sugar, and white sugar together until no brown sugar lumps remain. Whisk in the egg, the egg yolk. Whisk in the vanilla.
3. Pour the wet ingredients into the dry ingredients and mix together with a large spoon or spatula. the dough will be very soft. Fold in the chocolate chunks until they are evenly distributed.
4. Cover the dough and chill for 2 hours, or up to 3 days. Chilling the dough is mandatory.
5. Take the dough out of refrigerator and allow to slightly soften at room temperature for about 10 minutes.
6. Preheat the oven to 325℉. Line two baking sheets with Silpat or parchment paper.
7. Roll the dough into 16 balls about 3 TBS of dough each. The dough will be slightly crumbly. Roll the dough to be taller rather than wide so the cookies will bake up thick. Put 8 dough balls onto each cookie sheet. Press a few chocolate chunks or chips on top if desired for looks.
8. Bake for 11-12 minutes. The cookies will very soft and slightly underdone. Don't bake longer than 12 minutes.
Allow cookies to cool on the cookie sheet for 10 minutes before removing to wire racks to cool completely.
If you want smaller cookies bake for about 8 minutes. You can freeze the cookie balls and save for later. Bake frozen for 12 minutes.
From Sally's Baking Addiction