1/2 cup unsalted butter
1 12-ounce bag semi-sweet chocolate chips
1 1/4 cups light brown sugar, packed
3 large eggs
2 teaspoons vanilla extract
1/4 cup unsweetened natural cocoa powder
1 1/2 cups all-purpose flour
1 1/2 teaspoons baking powder
1/4 teaspoon salt
About 8 ounces dark chocolate, diced into 1/2-inch pieces
about 12 large marshmallows, cut in half
To a medium, microwave-safe bowl, add the butter, chocolate chips, and heat on high power to melt for 1 minute. Stop to check and stir. Heat in 15-second bursts, stopping to stir after each burst, until chocolate has melted and can be stirred smooth (Youíll likely only need 1 or 2 bursts).
Alternatively, melt the chocolate chips and butter in a medium saucepan over low heat, stirring constantly until just melted
Add the cooled chocolate mixture and beat on medium speed until just until combined, about 1 minute. Stop and scrape down the sides of the bowl.
Add the cocoa powder, our, baking powder, and salt. Beat on low speed just until combined, about 1 minute. Stop and scrape down the sides of the bowl.
Cover bowl with plastic wrap and refrigerate for 2 hours, or until dough has firmed up significantly. If you accidentally over-chill it and it becomes too rm, allow bowl to rest on counter until you can scoop it.
Preheat oven to 325F. Line a baking sheet with parchment paper or spray with cooking spray. Using a 2- tablespoon cookie scoop form dough mounds and place them on the baking sheet, spaced at least 2 inches apart (I bake 8 cookies per sheet).
Flatten slightly and bake for 10 minutes, or until edges and tops have just set, even if slightly undercooked and glossy in the center.
Remove baking sheet from oven, add 1 piece of dark chocolate to the center of each cookie, pushing down very slightly just so it breaks the surface and sinks down.
Place one marshmallow half on the top of each piece of chocolate on all the cookies, pushing down very slightly so the marshmallow adheres.
Return baking sheet to oven and bake for about 5 minutes, or just until marshmallows have puffed; donít let them brown and donít overbake. Cookies firm up as they cool.
Allow cookies to cool on baking sheet for about 10 minutes before serving. I let them cool on the baking sheet and donít use a rack.