1 1/3 cup granulated sugar
1 cup unsweetened cocoa powder
10 tablespoons butter melted
1 large egg
1 large egg yolk
1 teaspoon vanilla extract
1 cup all-purpose flour
1 1/2 teaspoons baking powder
1/4 teaspoon kosher salt
12 ounces semisweet chocolate chips
Preheat the oven to 375 degrees F, and line baking sheets with parchment paper.
Place the sugar, cocoa, and melted butter in the bowl of an electric mixer, and mix on low speed until combined.
Add the egg, egg yolk, and vanilla, and mix until combined.
Add the flour, baking powder, and salt, and mix until combined (do not overmix, or the cookies may not spread properly and/or could be tough).
Fold in the chocolate chips, and scoop balls of dough with a 1.5-tablespoon scoop onto the prepared baking sheets, allowing about 2 inches in between for spreading.
Bake for 10 to 12 minutes, or until the cookies are set around the edges but still soft in the middle.