INGREDIENTS
1 cup
butter
1 1/4 cups
brown sugar (packed)
1/4 cup
granulated sugar
1
large egg + 1 egg yolk
1 tbsp
vanilla extract
2 1/2 cups
all-purpose flour*
1/2 cup
unsweetened cocoa powder
1 tsp
baking soda
3/4 tsp
kosher salt or scant 1/2 teaspoon table salt
2 oz
semisweet baking chocolate bars roughly chopped
1 cup
marshmallow bits